The 2012 US GDP was 15.68 trillion. The 2012 Federal government expenditures were 3.54 trillion. Right off the top, the Federal government accounts for 22.6% of the economic activity in the country. Depending on how you measure, you can quibble with this exact choice of numbers, but no matter how you fiddle you're not getting out of the Federal government being a huge part of the economy directly. State and local governments still not counted in that number.
The Federal government also controls the Federal interest rate and its centralized currency directly. It extensively regulates every major financial industry; to the extent that this fails to produce sufficient "regulation" for a liberal's purposes, it is, generally speaking, not for lack of statutory power, and a concerned liberal should probably be looking at the (almost always) liberals exercising the statutory power, rather than complaining about the few people whose meager voices suggest that perhaps the power shouldn't exist at all, lost in the sea of those screaming for more.
Indeed, it extensively regulates every major industry. It produces thousands of pages of new regulations every year. It taxes nearly every economic transaction. You can't hardly do anything without the government being involved. It already engages in huge wealth transfers every which way (even some really crazy stupid ones, like Obamacare's transfers from the young and healthy to the on-average wealthier older crowd).
This is not necessarily and automatically a bad thing. I'm just mentioning this stuff to show that the idea that we live in some sort of libertarian nightmare is ludicrous nonsense. The state has the power already, today. It's not theoretical, it's a done deal. If you don't like the outcome we're experiencing, take it up with the State.
Personally I can't help but observe that we keep giving more power to fewer people under the rubric of "better government", and, lo and behold, our society has ever more power and wealth concentrating in fewer and fewer hands. Why, oh why ever could it be? Somehow some people manage to convince themselves this is all the libertarian's fault. I'd suggest looking at the people who keep putting more and more power in fewer and fewer people's hands and then acting all confused about the outcome where more power ends up in fewer people's hands. There might be a connection there. We might want to consider, you know, not doing that more if we don't like the outcome we're getting.
Much of the reason why I am a libertarian is that I actually think it's a good thing for society, in precisely the ways that David Simon is complaining about. With the bloated Federal government taking all the power, the government not only doesn't solve "the problem", for whatever problem we're talking about, but it also often prevents you from solving the problem. It can do this either legally, where it claims for itself exclusively the power to solve the problem, followed by it either doing nothing or doing the wrong thing, or perhaps more poisonously, it convinces you that it is its responsibility to solve the problem, followed again by not doing so or doing the wrong thing.
A couple of days ago I happened to flip by the Canadian Broadcasting Channel's news hour, and there was this guy standing in front of a children's playground, complaining that the city wasn't taking care of it. Scattered on the playground were about 30-40 bagged piles of doggy-doo-doo. It otherwise appeared to be a fine playground; it was modern, the paint was cared for, the swings were all there, it did not show obvious wear. He's standing there talking to the reporter and complaining that their part of the city needs more money. My crazy, socially-evil, society-hating, collective-despising libertarian anwser was "Dude, in the amount of time you spent complaining to the reporter, you could have just cleaned up the playground." Seriously, all that was wrong with it appeared to be scattered piles of, and again I emphasize, bagged doggie-doo. This is how the government can corrode away the very social consciousness that people so desparately try to use governments to create. Yeah, it's a small example, but it happens everywhere, for all kinds of things.
(Yes, I realize that cleaning it would then mean the guy couldn't complain, so he's putting on a show. I further realize that it's really quite likely that the doggie-doo receptable probably had all the doggie doo piled up in an somewhat unsanitary pile, and the guy probably deliberately scattered it before the video shoot, because really, scattered bagged doggie poo is a rather unlikely scenario. However, I'd suggest this just further emphasizes the point I was trying to make here. You can't create "social responsibility" by telling everyone that somebody in $GOVERNMENT is going to take care of "it". You create the exact opposite. If you want more social responsibility you need less government.)