Of course people have asked for, and received, discounts from these people. If I go to a barber weekly, they likely will give me a different price v monthly. Same with a mechanic—price matching for services etc. As for a dentist, 4 cleanings a year may be discounted which are not all covered by insurance or a cosmetic procedure may be discounted when not covered by insurance.
so yes escorts are not unique—it’s a business. Escorts operate their business the way they want and some may offer discounts for various reasons unique to them. Good on them for figuring out the best way to operate their own business in a way that makes them fulfilled.
and while a client may not presume a discount will be offered, they can ask. I don’t get offended when someone asks me to discount my rate for the consulting work I do. If I want to discount, I tell them yes. If I don’t, I tell them no. And different things Drive that.