and don't want their face photos out there, as well as hobbyists who want to remain discrete and don't want their photos out there. If someone screenshots the facetime session, who knows where those pics might end up.  

As far as verification, the only thing that facetime would verify is what the person looks like. That is not usually what providers are concerned about when screening.

Seeing your face wouldn't tell her if you're a safe guy to meet. If she wants to hear your voice or just talk to you first a phone call accomplishes that. If she wants you to see her face she'll have photos available on her website or ads. If she prefers not having her image out there face time would be a bad choice for her, and what you look like usually doesn't matter.

I agree that it really has no benefit for providers. However, it might be useful for client verification/screening I suppose.

A