Yeah, good point. Here are the explicit guidelines: 3.1.3(d) Person-to-Person Services: If your app enables the purchase of realtime person-to-person services between two individuals (for example tutoring students, medical consultations, real estate tours, or fitness training), you may use purchase methods other than in-app purchase to collect those payments. One-to-few and one-to-many realtime services must use in-app purchase.