Haha, it would be quite a coup for tech to disrupt the "world's oldest" industry.
I imagine that doing something across jurisdictions could actually make things worse (I'm speaking as a non-lawyer and general ignoramus here). Maybe if you maintained plausible deniability at all times. Might be worth consulting a lawyer considering the size of the industry ($$$). OTH, there are other potential sources of liability than legal (going up against organized crime might prove more difficult, than say taxicab unions, for instance).
I mean, I think the way to do this would be to pitch it the Canadian equivalent of the Health and Human Services department--they host the app backend, and offer scheduling and reservations, and send health checkup reminders. In return, they get to monitor the profession and help encourage safe sex.
I imagine that doing something across jurisdictions could actually make things worse (I'm speaking as a non-lawyer and general ignoramus here). Maybe if you maintained plausible deniability at all times. Might be worth consulting a lawyer considering the size of the industry ($$$). OTH, there are other potential sources of liability than legal (going up against organized crime might prove more difficult, than say taxicab unions, for instance).