> During the hiring process, on-call is not mentioned in any way other than the usual salaried catch-all "are you willing to work nights and/or weekends."

It should be very clear what the actual expectation is, though, instead of a nebulous "we may need you to work extra sometimes." It's a guarantee that you will work extra at a fixed interval, and that extra work happens to be psychologically draining.

I ask for quite the premium in salary if I know I'm going to be on call.