Agents and agencies were abundant before Internet. They still exist, not only in Prague but also here in the US.
This guy:
http://www.daddysreviews.com/review/jonah_fox_dc
He is now retired. I had even published his review in my blog but he called me and asked me to put it down. He had an agent. The owner of one of the current escort websites, I never remember the name, jokes something.
I asked him why to have an agent in Internet era. He told me that the guy would handle all of his Internet communications and ads (he used to have an ad in jokes something and in friendboys.pro), and his fee was 10%.
A business model that seems not to make sense. Totally based on honors, as the agent does not control contacts with clients as the old agencies used to.
But the point is that there are escorts in the US who do have an agent.