This has resulted in payment processor execs historically being very prejudiced about against any site that provides that sort of content.

Combine this with the dual facts that no one of good standing is very motivated to stick their neck out to defend porn publicly, while many people define their politics by being very publicly against it, and you get a system that routinely discriminates against sex workers.

[1] Historically, this was from angry spouses/parents seeing it on the CC bill and the person who ordered it lying that "someone else must have stolen the card and ordered it"; nowadays actual identity fraud is so common that it's a real concern