I think every reasonable person accepts that human beings need some sort of government. The law of the jungle works decently for the Alpha lion in the prime of his youth, but it screws over pretty much everybody else. So we all accept that we need some sort of official association to keep the alpha lions and other predators in check. This is the function of government undertaken by our police and military forces. Since a group of organized beta lions can easily keep a single alpha in check (not to say that there are no alphas in our military, but rather that even if the strongest person wanted to impose his will on society it wouldn't take more than a dozen or so average people to restrain him) this works pretty well and, in a functional society, people feel relatively safe. Of course there are always problems, primarily that police function is at its core responsive and also that it is possible to evade, but few people disagree with the principle of armed protection for the citizenry. (There are many people who take issue with how this protection is recruited or utilized, such as those in militias who fear government repression for what they believe to be legitimate actions, but I've yet to meet anybody who wasn't a complete loon and believed that in the realm of personal protection every person should stand for himself.) Furthermore, most agree that this protection should be extended to areas outside immediate physical harm, like protection from fraud and theft.
This is the minimum required to have a functional government, and it's pretty much what we had in the middle ages. The monarch made a few efforts to protect the populace from being murdered by rampaging hordes, and beyond that left it to its own devices, except when he wanted to claim his taxes or claim the right of prima noctae. Of course many local lords took it upon themselves to do nasty things to those under their purview, and there was always the church doing its incredibly complicated churchy thing, but the basic idea remains the same. The government was responsible for physical safety, full stop. This, of course, has changed over time. We now expect quite a bit more from our government. Some of it seems like a natural extension of the policing function. Fire departments, some sort of emergency medical care, civil courts, that sort of thing. Some of the functions are a bit less limited, and here we find things like public works and road maintenance. These are functions that could reasonably be carried out by private individuals, but that most people would agree are best left in the public sphere. We've had privately held transportation channels in the past, most notably in railroads. It was a bit of a mess, with all kinds of different gages being laid and a lot more transfering from train to train than people liked. Eventually government supported companies emerged, became huge sources of graft, and laid the track that modernized the nation.
In point of fact, many of the great companies that forged America's industrial past were induspitably aided, or even reliant, on the government. From land grants to mineral rights the government has always been a part of American capitalism. We like to forget this, to claim that these were companies that made their fortune through hard work and smarts. Hard work and smarts (along with ruthlessness and a loathing of 'lower' humanity only matched in modern times by televangelists) did play a part, but so did government intervention and support. Many of today's great businesses relied on government orders to grow themselves to a respectable side. Even Microsoft can be traced to a government program. Bill Gates' father went to college on a GI bill. Without that it is unlikely he would have been able to give his sons the advantages that allowed him to explore and grow his intellect to the point where he was able to create that massive company.
As you may have noticed, we've now slipped past public works and into the realm of public largesse, the area that Williams declared no different than outright theft. Here's the thing, though. There are no great fortunes in America that can not be traced back, in large part, to government largesse. It just can't be done, because in early America almost everyone recieved government largesse. The settlers who went west got land. You could argue that the land was just there for the taking and the government wasn't really involved (The injuns might not agree, but we tend to ignore them except when we realize that we're ignoring them and then we pay them lip service) but that's not the case. Government enforced land rights, provided postal services, and did all sorts of other things that allowed those settlers to survive and prosper in much greater numbers than those who recieved no external governmental support, such as the piteous dead of Jamestown. So, to say that the government should cease all involvement in distribution is rather silly. It's saying that we should accept the way that things were carved up back then, even though it was unfair and blatently disciminatory, and move on. Kind of silly, in my view.
Of course government redistribution of goods doesn't rest solely on the "well everybody else did it" principle. The more important principle it rests on, at least for me, is the fact that property rights are among the least important rights in a society. There are people who believe that the right to property is up there with the right to life, freedom from slavery, and freedom of speech. I do not. If you take away my Xbox I'll be upset and possibly angry. If you take away my freedom of expression, I will be devastated and fight you to the death to win it back. There are many rights that trump property rights, and among them are the right to food, medicine, and opportunity. People like Williams claim that food stamps are a form of theft, but I ask what right the baker has to keep his bread away from the mouths of hungry children? Because he baked it? Because he owns it? I think he has no right to plenty while others are starving. He can feed and care for his own family's well-being first (keep enough bread to trade for warmth in the winter, clothing for his family etc...) He does not, however, have a right to luxuries if there are others whose health is in danger. As a society it is our responsibility to provide for the least advantaged and even the laziest among us. If you want to call that pulling a "Robin Hood" and robbing the rich, I think that's fine.
Basically it boils down to this. It's only through having a stable government that promotes economic development that large numbers of people become prosperous. Governments like that have a responsibility to take care of their citizens. If that requires people who can afford it to pay back some of their money to the government so that it can provide services to the less-fortunate, that should be a non-issue. It's not thievery, it's just payback, and on balance it's good for everyone. The government does have a responsibility to be a good steward of the people's money, but there's a difference between good stewardship and complete non-interference.