I think it's naïve to think that these girls are only very strictly selling feet images and are not in the business of having sex for money as well.
Especially when you consider the top-heavy success distribution. Sure there's influencers that have 100M views, but theres thousands of influencers with 300 views, are they going to be just happy with selling pictures for 10 bucks? Or will they follow the whales until they are paid to be flown into the prostitution assembly line, with or without visas.
Apparently porn is sex for money, but legally it's not prostitution. So in that case, these OF influencers can just bill their private services as coaching lessons for aspiring actors.
No one said law was consistent or made sense.