One thing you notice from time to time - and particularly in "you didn't build that" exegeses - is that people who have been (rightly) convinced of the efficiency of voluntary market exchange as an organizing logic for society have a very hard time accepting other voluntary logics that don't work quite as smoothly as market exchange. That seems like a shame to me.
We shouldn't jump straight to government. Let's keep it in the private sector - you see this even with skepticism about charities sometimes. Sometimes people who (rightly) appreciate market exchange will make the critique that although charity is voluntary and private, the fact that the needs of the recipient aren't explicitly taken into account hurt the case for charity. This will often lead people to consider aid to Africa hopeless, or scold you for giving a homeless person food instead of just giving them money (which is more comfortable for someone that's thoroughly ingrained Kaldor-Hicks into their ethical sensibilities). One can go further than that: see Bryan Caplan on the deserving poor, Ayn Rand on altruism, and Malthus on charity.
When you get into government it's often no longer just a cataloguing of the differences between market order and government, it can be an outright denial that "government" and "voluntary" should even be used in the same sentence. And that's really what I have a problem with. I'm not one that promotes socializing everything. I know the limits of political allocation and the problems with majoritarianism. That's not in dispute. My concern comes in when people using government to solve their problems and constitutional democracy aren't even considered voluntary versions of an admittedly problematic organizing logic.
In the market, we choose voluntarily as individuals. In a democracy we choose voluntarily as a community. There are costs and benefits to each. The communitarian nature of democracy prevents democracy from being good at supplying private needs. The individual nature of the market prevents the market from being good at supplying collective needs. This seems to offer a liberal solution that - in practice - will always be a contested one, but which nevertheless is characterized by a relatively straightforward division of labor between the public and the private sphere. The fact that the contours of this division of labor will be contested can be ameliorated by democracy itself, federalism, constitutionally limited government, and free movement and speech. This is the classical liberal position and the position of the American founders.
Unfortunately there are a lot of people today who couldn't write that about government but who nevertheless claim the classical liberal mantle.