Yes, they would, and they do. The difference is that they aren't dealing with another government. It is one thing to refuse an official envoy from another government to come into your nation. It is quite another thing to refuse a church or a charity. Refusing another government is generally acceptable in the world. Churches specifically, and to a lesser extent other charities are much harder to refuse. You'd basically have to seal the borders from all foreign visitors. See, another government coming it can be seen as an "invasion" or at the very least it has a political stamp on it. A charity which has no official governmental power, isn't likely to overthrow a world leader or damage their country. Consider this, let's assume that 1% minority of a nation's population observes a certain religion (especially a religion observed heavily in other nations). The government of that nation may oppose that religion, but they run a huge risk if they openly preventing that religion from practicing it. They can try to make it illegal, but that doesn't really stop the faith. They can try to persecute the religion's followers, but that tends to make the followers martyrs. Religious people are generally allowed in and out of nations, even when the religions themselves are illegal. Those religious people can bring supplies and even food with them on missionary trips (this is done quite regularly). If the government opposes these missionary trips, or if it confiscates the supplies, the worldwide religion's headquarters issues press releases and people around the world are made aware that this government is restricting their religion. This tends to get media attention. The media is generally against religion today, but they will report on government oppression of religion, and media is generally allowed to go into any country with few restrictions. The point of this is that the government that doesn't care about feeding its people and would refuse an outside government is suddenly under worldwide scrutiny and the world becomes aware of what it is doing. Tyrants hate a free press. They'd rather be secretive and they'd rather that nobody knows what is going on. At that point, one of a few things might happen.

1) The government might simply have to allow the food shipments through as part of the religion's missionary work (this is the least damaging in the short term to most tyrants).
2) The government can blockade their own nation (which is somewhat different from an outside nation blockading them).
3) The UN may have enough backbone to get involved (not likely, but who knows?).
4) Enough worldwide support might be raised to cause the government to make a policy change or a priority change.
5) There may be a change of government in the nation.

Still it is possible that the charity won't succeed. Nonetheless, it is more likely to succeed than an outside government unless that outside government is willing to go to war over the issue.

Look, the sad fact is that no single nation can militarily take on the whole world, or even all of the tyrants and dictators that treat their people badly. The United States has a decent sized military, but it cannot support campaigns in the dozens or even hundreds of nations where people are starving and the goverments aren't doing anything about it. Even if that is all that the US military did, we couldn't do it all by ourselves.
You need multinational backing, and many nations will oppose you for many different reasons. For example, we don't do anything militarily in the Sudan, despite their obvious disdain for humanitarian concerns, because many nations trade with Sudan for goods that they produce cheaply there. Yeah, that's pretty sad, but it is a reality. The UN, and other nations, wouldn't likely back a campaign there. For that matter in 2002, Sudan was added to the UN human rights commission and the US was kicked off (the US was reinstated in 2003, but Sudan is still on that commission despite what goes on in their nation).

It takes more political will than exists in the entire UN to overthrow a tyrant. That kind of will is hard to come by. When it is found, you normally see a huge reaction against it. Generally speaking, the world would rather not go to war and would rather not stir up trouble because they don't really consider that the lives of people in some other country are worth as much as thier own comfort and "peace". This is the "peace" of the grave that they support, but they don't see it that way.

Lets say that you are president, and in the ficticious country of Tyrrania, the leader is a tyrant who is building a military and living in luxury and allowing his people to starve. Would you support a war against that nation, a nation which has never attacked your country? Would you support that war even if the rest of the world was against it? Would you want UN approval? What if the UN didn't approve? What if some business people from your own country did business with that country and further, what if those same business people contributed to your campaign for President and are demanding their political favors in the form of you not pursuing that country (most politicans fail at this one)? What about if your State Department says, "let us negotiate, we'll get the job done and it will make the US look good in the international arena that we can do the job with diplomacy instead of the military."?

I'm with you, let's fight them all, I don't know where we'll get the troops, the money, the supplies, the international support, etc. But let's do it anyway. Sorry, but the reality is that all of these things, troops, supplies, money, etc. are all in limited supply. Anything in limited supply is restricted to the laws of economics, so we have a situation where we can only fight one war at a time (actually the US is supposed to be able to fight 2 major wars at one time, but In the '90s, the President stripped down the military so that it really can't do that at this time). We instead need to pick our fights carefully and get as much international support as possible. If we don't, we'll find ourselves out in the cold on the International scene, with everone else in the world against us. For that matter, if we tried to do this, the media would be wholly against it as well.

Unless you can find another approach, people are going to die starving while we handle this problem, one nation at a time, and it will take leaders of strong moral fiber, who aren't swayed by politics, to do it. You can tell such a leader because they tend to take strong stances on moral issues, they tend to be proud of their beliefs and they tend stick to them even in the face of bad press and poor support.

Agreed, people should talk faster, starting with those who are resisting the aid. Oh yes, those would be those foreign leaders who won't help their people, and the UN who can't seem to take a stand. If only people did the right thing, but you do understand that you can't make people do the right thing, don't you?
The leaders of these nations know their people are starving. They don't care. If they did care, they'd spend their money on their people instead of on weapons or yachts or whatever. If they cared, they'd build an infrastructure that could help support their people. They're there for power and luxury and a bit of warfare and tyrrany. They aren't there for their people. No amount of talking will change that.
Fists (military involvement) would always be more expedient, please tell me how to pay for it and keep the world opinion and domestic opinion positive at the same time.

Wow, what a gloomy reality I just painted. There are good people in the world who want to fix this. You find many (most) of them in charities and churches. Think about it.

-- Jeff

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"Government is not the solution to our problem, government is the problem." --Ronald Reagan