While camming may very loosely fall under prostitution laws in some states, it's not something that any law enforcement would bother wasting resources on.
For example, in Iowa, the state I live in, prostitution is defined as "stimulation of the genitals of another or oneself for the purpose of sexual excitement in exchange for money", (not an exact quote of the law, but basically what it's saying). But is anyone going to arrest me for fapping on camera? No, they have bigger fish to fry.
We have a lot of laws on the books that nobody enforces - for example, BDSM is technically illegal in Iowa as well, as it's against the law to give another consent to harm you. Nobody has been arrested for that for decades, and we have a flourishing kink scene, because law enforcement just isn't going to be bothered to do anything about it.