Society's desire for regulation of behavior ebbs and flows.

Not limited to the US:

prostitution was legal and then it was not and now there is a laissez-faire of some kind in some places, in others there are brothels, in others you cannot, strictly speaking, but in practice it is whatever;

The consumption of alcohol was initially allowed, then forbidden, and later allowed again. Nowadays, some "thought leaders" are again somewhat pushing, if not for regulation, for public condemnation;

Abortion, same-sex sexual relationships, gambling, drugs, they all follow a similar pattern of regulation-liberalization-regulation- (random order), answering to "society" or some prominent voices within or the ever fleeting vibes of the times.

In other words, it does not make, strictly speaking, sense that certain behaviors are regulated or prohibited, and others are not.