Most madams do the same job as many pimps, just a gender difference. Like used car salesmen, they can be good or bad.
Many women who are too clueless or can't be bothered to run their own affairs properly will in effect choose to employ an agency or other intermediary, even at 40%, just to take care of marketing, appointments, venues and so on. The law doesn't like that voluntary arrangement between competent adults so tries to criminalise it, or associate it with coercion and other activities involving abuse and non-voluntary arrangements. A 'pimp' is culturally associated with the less desirable examples of prostitution, where the prostitute is literally (rather than legalistically) 'controlled.' Most of that culture comes from that bastion or prurience, the United Fucking States of Fucking America.