It's very rare for rape to be a legally mandated punishment, which I think makes it an "unusual punishment," even if it's not a particularly unusual occurrence

It's very rare for rape to be a legally mandated punishment, which I think makes it an "unusual punishment," even if it's not a particularly unusual occurrence (either among the punished, or among the world at large). A couple thousand US prisoners have died of covid and hundreds of thousands have been infected with it, but that doesn't mean that intentionally inflicting people with covid is now a usual punishment.