The difference is in the eyes of the beholder.
In Uruguay prostitution is legal but having an agent sending you here and there or charging you a commission to use his place is illegal.
In most European countries prostitution is legal including brothels, in others is not legal.
"The top quarter of guys". I might like guys you don't like. How can you point at some gays and say they're the most wanted/hired/successful escorts in one city? How can you collect the date to determine that?
I never read a review on here starting with "his agent made plans for my meeting with XXX".
I'm not saying what you say it's not true, maybe in Prague is done that way. Here there was an agency called "DC boys" and another one called "Top referrals" but I'm talking about early 2000, a time when cellphones weren't as common.
When you say most folks do this or that I would take your word with caution. You have some perception issues when it comes to reality: urban decay all over the U.S.A., some folks from one tiny country in the Middle East being the most hatred folks in the world, etc. When you talk about a friend of yours you remind me of Trump telling a story.
Those providers can learn English. If someone from South America was able to get a visa to come over here he certainly didn't come out of a "villa miseria" (shanty town) in Buenos Aires, a "cantegril" in Montevideo or a "favela" in the 'morros' (hills) of Rio. If he had some High School I'm sure he speaks some basic English. Besides he prepared himself for his trip and made an effort to learn some useful words. Reading/writing a language is easier than speaking it and understanding it from a native speaker, most communications now a days is done by text.
You don't need to super intelligent to write down you'll have someone on Saturday at 2, if someone calls and ask for 3 PM that same day you can always suggest: "What about 3:30 or 4?" You sound a little bit condescending on this matter.