I guess there is also a numbers issue; most escorts are women, and most women are either totally straight to straight leaning. I wouldn't be surprised at all if a larger percentage of escort are bisexual, than the broader population but its still finding a niche of people within a niche, before you get to all the other general compatibility stuff. And straight/straight-leaning male escort/sex workers aren't really a thing, other than a few wannabes and posers here and there.
I totally get you though, after lots of dating issues relating to my profession, I've often thought, wouldn't it be nice to date/build a relationship with another escort theoretically at least.
You could try set up a WhatsApp group or something similar for bi/lesbian escorts open to dating, which might make the 'niche in a niche' thing less of a problem because something digital is less location restrictive.