I suggest you go out and talk to some actual sex workers, with an open mind. I know (socially) a few former sex workers, and they would vehemently disagree with your characterization. The world is way, waaaay more complicated than you seem to think.

Which characterization? I made two. I disagree with your characterization that "sex work" is "waaay complicated". Putting together a lego set is more complicated.

"there is only ever one willing consenting party"

This is demonstrably untrue.

"Trust me" isn't exactly a convincing argument...

I agree with your second sentiment (although I wouldn't generalize to "scumbags"), but there are a lot of people out there doing jobs that are extremely unpleasant, for far less money than prostitution can make.

If you don't have to fear your customer because the legal system has your back (making you independent of pimps and the like), prostitution is a possible way to make a significant amount of money - on your own conditions, in your own time, without the fear of being fired and all the other stuff a normal workplace imposes.

Okay, so now there's one consenting party instead of zero.

I'm sure the telemarketer consents.

Not really, they are under economic coercion.

My, aren't we all.

If one isn't rich one shouldn't be considered free..

Also consent can now be retro actively withdrawn, so if you don't keep your books, your hooks will bleed you.