For context, I'm a left-wing Canadian socialist.
1. Drugs should all be legal as Portugal's legalization of all drugs has shown us the war on drugs is a massive boondoggle. [1] So has Canada's legalization of marijuana.
2. Child employment is legislated on the basis that children aren't able to make their own decisions, and that sounds ok.
3. Heavy metals, I assume you don't mean the music, is regulated to protect the welfare of the entire population.
4. Contracting?
> I think the probability of women wanting to corner the market for sex is low.
I can't think of a single reason to legislate consenting adults exchanging money for sex. It's not for me, but as with the war on drugs, the medicine is so much worse than the cure it's time we dropped it. The only thing harmed by regulated, clean and safe prostitution is property value and puritanical sensibilities.
Especially when scientists taught monkeys the value of money and they first thing they did was exchange it for sex. [2] That might be the most fitting epitaph for humanity yet, actually haha.
[1] https://www.theguardian.com/news/2017/dec/05/portugals-radic...
[2] https://www.zmescience.com/research/how-scientists-tught-mon...