Sure, I'm not arguing that we don't ban contracts between consenting adults. But I think we should be highly suspicious of them.

> - Contracts for the sale or distribution of controlled substances, such as drugs or drug paraphernalia; + Gambling

Consent is a gray area due to the addictive nature of the what the buyer is buying.

> Prostitution

We do ban this, mostly due to I think society finding it icky.

>- Employment contracts that permit hiring underage workers.

Not between consenting adults.