Usually it's just escorts, security guys (who double as drivers), receptionists/screeners, and the owner, who generally does the accounting. I do bi-weekly drops, where I take out the 30% I owe the agency and either give it to the owner if she's around or put it in an envelope and drop it in the safe. Occaisionally you hear about escorts skipping town with their agency's money, but it's a stupid thing to do when, instead of stealing 30%, you could just work an extra week and make a ton more money. An escort who steals generally won't ever be able to work in that city again.
Most people hold other jobs or do work-from-home stuff. Escorting can be very profitable part-time. A lot of people just tell others that they're strippers; it's a good way to explain having lots of cash around and working flexible hours. The security and phone people generally work under a very blandly named business name, like (am making this up, but it's pretty typical) Star Administrative Solutions or something.