I think you are naive about the risks, and maybe about the impact. You are also talking like a hero about a very scary choice and most people aren't that tough. Easy to act tough online, much harder to play chicken with a real prosecutor wielding a real threat of prison.I'd happily take a 1 in 1000 chance of being caught lieing in court
An SP could testify against a couple of johns and the overwhelming majority of her customers would never know. I can't see it stopping her from continuing to work. It would cost her a few customers. Nothing more.