Since every individual carries out any job to earn money, he practices prostitution to all intents and purposes. Selling your sex organ is no different than selling any other part of your body, like your voice, brain, muscles, and more, just to get money.
More like union busting strike breakers. There is a supply union, with rationing, but the free lancers are providing supply against union scarcity rules. So those in the union dislike the strike breakers.
There’s a lot of different nuance takes out there, but I think this is one of the main sources of animosity of this employment group. In some societies it’s totally fine, and other societies, typically more religious societies, it’s very much frowned upon - partly because of this union approach. We control the supply side how dare you provide supply outside of our rationing system.