I also imagine that only psychopaths actually rape.

Don't think that, unless in so thinking, you also think that "a psychopath" can be a functional, indistinguishable member of society who you'd never once know even through extended association unless he happened to tell you about that one time at that frat party (or whenever).

This. I know or have known three people who survived rapes and were comfortable enough with me to tell me details of the situations. One was in a mental institution, and was raped by the staff - I don't know much about the details in that situation, but the person or people involved were indistinguishable enough to be employed in that situation. Another friend was assaulted by her twin brother when they were teenagers; other than that, to hear her talk about him he doesn't sound psychopathic at all. The situation I know the most about involves a friend who, as a teenager, passed out from hunger in the presence of a male acquaintance - almost a 1:1 correspondence with the 'lost wallet' scenario. We've talked at some length about him, since he tried to get back in touch with her recently, and while he has quite the sense or entitlement and is in denial about the situation, he's pretty definitely not a psychopath. (Unless I'm very much misremembering my research on psychopathy, psychopaths don't do denial in the same way he was doing it, if at all.)