I think the "body" in that expression is quite specifically referring to genitals, or the selling of your intimacy.
Because that's what's different from any other physical labour, the part of your body involved. That's the specific problem of sex work no?
Therapist is another topic, with problems of mental intimacy indeed.
The rest is the patient's intimacy that you have to deal with. It is a vastly different intimate experience to wash a genitalia and be penetrated. And so, vastly different consequences for your well being.