> I'm using regulation in the sense of preventing destructive behavior.

Which is impossible. The best we can do is to give people as much incentive as possible not to engage in destructive behavior. The best way we know to do that is a free market. It's certainly not perfect but the alternatives are even worse.

> We're not talking about price control.

I said prices were just one example. Any "regulation" other than voluntary transactions in a free market has the same issues as price control does: it masks essential signals.

> Monopolies for one are inevitable in pure free markets.

On the contrary; monopolies are short-lived in pure free markets, because the conditions for natural monopolies are rare. Long-lived monopolies only occur because of government regulation. The original meaning of the word "monopoly" was a royal privilege granted to certain people to be the only allowed sellers of particular products.

> Your assumption is that ALL suppliers will by some magic willfully expend the effort to provide people with safe milk.

I made no such assumption. You were the one making an assumption, namely that the conditions imposed by government regulations were the optimal ones. (As I explained before, you also implicitly assumed that everyone had the same preferences, which is necessary for a "one size fits all" regulation to even possibly be optimal.)

> I will argue that no reasonable average person is equipped to reliably determine what safe milk is.

Really? Then how did people manage to do it for the thousands of years that milk was produced and consumed before we had microbial testing labs?

> my rights of not being subjected to aggression thump your rights to choose specific levels of bacterial content in milk

No, your rights of not being subjected to aggression trump my infecting you. So if I consume tained milk, and get infected, and infect you in turn, you have a valid claim against me for restitution. But that in no way demonstrates that the government is justified in preempting me.

> I'm not sure what are you referring to.

Look up how those mining companies, for example, got the rights to mine a specific area. They were given exclusive rights by governments (usually state or county governments, depending on how the land ownership was handled).

> So basically your argument is ... because people had their freedom taken from them by some who then proceeded to sell and buy them, effectively turning them in commodities - this can't be used as an example of buying and selling?

No; once again, you're not reading very carefully. The transaction that was involuntary was the initial enslavement of the slaves; they didn't voluntarily choose to be slaves. If their enslavement is taken as given, the transactions in which they were bought and sold were obviously buying and selling. But in a free market, you can't sell something you don't have a right to in the first place; and the only way to gain a valid right to something is to either produce it yourself, or buy it from someone else in a free market transaction. Since the slaves did not originally become commodities by a free market transaction, no transaction in which they were subsequently bought and sold can be a free market transaction. It can be a legally allowed transaction, but that's not the same as being a free market transaction.

> There was a need for labor in the market, and the market happily fulfilled the need

Not a free market. See above.

> The fact that governments eventually taxed this trade (I'm assuming this is what you mean by "governments legitimized it")

No. You are apparently very ignorant of the history of slavery. It has existed as long as civilization has existed; most wars for most of human history have ended up with the winning side enslaving the losing side. Governments legitimized it by practicing it directly. Offloading the grunt work to private companies or individuals and taxing the proceeds was a later innovation.

> it was a practice already very well entrenched

By governments. See above.

> I hope you are aware that slavery did not start or end in the US

Of course I am. See above.

> in fact it predates by a lot most forms of anything which would resemble a government.

This really depends on what you call a "government"; city-states at the beginning of civilization already had governments in at least some senses of the word. But even if we use a narrow sense of "government", it is still true that most governments in human history have practiced slavery directly, as I described above (by enslaving populations they defeated in wars). They certainly did not confine themselves to just taxing it. As I said above, that was a later innovation.