It's clear asking a professional to do this and not being up front about paying $0 is unprofessional and a disrespectful waste of time, but I'm not convinced it

It's clear asking a professional to do this and not being up front about paying $0 is unprofessional and a disrespectful waste of time, but I'm not convinced it's actually predatory or abusive. If someone thinks they'll get more than $their_cost in promotion value, they'll do it. If not, they won't. If no one does, the production company is going to waste a lot of time and burn their reputation trying to avoid what's probably a relatively small expense compared to the budget of their show. It would be even worse if someone wrote an article about it.. oops.