People wouldn't mind free market radicalism so much if they were restricted to just those things in which a free market is possible. Otherwise, you can enjoy deciding which broadband provider you're going to choose, when there's only one set of cables serving your region - or any of the other great 'decisions' you can make when confronted with monopoly.

Or, you can nationalize, and give monopolies to an organization precisely designed to manage monopolies (primarily the monopoly on violence) in a way that's more or less livable.

We're straying away from the point here, though. I think it's obviously possible for companies to exist that serve no good whatsoever. Companies exist to make money. Unless there's an apriori link between some people making money and universal good that I'm unaware of, there's no way you can step around that. Therefore, making taxes zero will always be an unfair deal for some people - since there will be some companies that contribute nothing, and yet use resources and services provided by the government.

Obviously, you could have a mad-max style anarcho-capitalist system, or something, then all my concerns would be void, but probably soon, all your concerns would be too - and all of your neighbors, except that guy Benno, with the gun collection.

The issue here is that there is no such thing as an objective "universal good"; that's just code for "things of which I happen to approve". The closest analogue which actually does objectively exist is "actions agreed to by all participants which do not actively harm anyone else". Granting the participants the barest courtesy that they are in the best position to know their own concerns, such actions can be considered at worst neutral and in general a net-positive on the basis that the action would not occur if anyone affected by it did not see it a priori as being in their own best interest. Others may not perceive the action as "good", but as these others are by definition not impacted and thus have no standing in the matter, their opinion is irrelevant. Participants may be wrong about whether the action will benefit them, of course, and you are welcome to attempt to persuade them to your view if you feel their judgement is in error, but right or wrong this is ultimately their decision to make, not yours.

Obviously actions which harm non-participants should be out of bounds—that's something the anarcho-capitalists (a.k.a. libertarians), minarchists, and most others can agree on in principle, though for some reason only the anarcho-capitalists are consistent in applying the same rules to governments. With that caveat, however: companies exist to make money, and they do so by engaging in voluntary trades that each participant expects to benefit from. These trade are thus both individually and collectively a net benefit to the participants and either neutral or beneficial to everyone else, according to the only objective measure available.

If your happiness depends on others doing only those things which you consider "good", and not what they collectively see as their own self-interest, then I'm sorry but I really don't know how to help you. This is harm you cause to yourself and not any result of others' actions.

I guess here is where we part ways. I can understand it in the sense of objective morality not existing, but I don't think it makes sense to say there isn't a common good. I don't know what the word good means if it doesn't refer to something that happens between people.

I think it's a basic function of groups that they establish what is and isn't good - that forms customs, then law. Obviously, this is a flawed process, but I don't think it makes sense to go total nihilist about it, and just say because you can't prove positive and negative outcomes about given actions, you shouldn't try.

We're fully capable as a society of discussing outcomes of various actions and laws - and that's what we've been doing since the beginning of time. You're doing it yourself when you say 'actions that harm non-participants should be out of bounds'. You're just drawing arbitrary boundaries around the few rules anarcho-capitalists consider sacrosanct[1] and saying that these are obvious, while others are matters of personal opinion that are indeterminate.

I think the idea of 'voluntary trades' is also a bit strange. All trades have side-effects, and most trades are with an element of coercion, natural or otherwise - people need food and shelter, they can't simply not trade for them. So even if you freely trade to build a dogfood factory next to my house, I'm implicitly part of that trade, because I live next door (or if you push the argument along, we're all implicitly involved in basically every trade, because we live on the same planet - e.g. global warming).

[1] - by the by, but I'm pretty sure these rules wouldn't be enough. If you look at early modern history, you can see that a lot of state formation was driven by the needs of capitalism - as states respond to one crisis after another.