1. Sex is a fundamentally asymmetrical power dynamic. For a conventional porn actress, it's frequently something that's done to you. These sex workers become passive actors in a transaction that directly taxes their mind & body, something very rare in other industries.
2. Sex work comes with a hefty opportunity cost. Any reputation you create for yourself in the sex industry becomes toxic once you leave -- and eventually you do have to leave it. It's a job that consumes all of your prime working & education years in exchange for little, if any, future opportunity.
3. Sex work is often, by far, the most lucrative job available to a young woman. Some young women simply have no other realistic choice to pay the bills. This in and of itself isn't a problem unique to sex work, however it does uniquely suck for sex workers because of the prior two issues. How do you stand up for yourself when the other party knows you can't walk away? How do you save for the future if you need the money today?