I can't think of a single job/interview/offer where the expectations or the compensation for on call were discussed formally, let alone agreed. The best I get

I can't think of a single job/interview/offer where the expectations or the compensation for on call were discussed formally, let alone agreed. The best I get in job interviews is usually a mention that there is a rota every X period. Then have to poke interviewers trying to guess what is it like without coming up as too negative, "when is the last time you worked on a week end?" "when is the last time you were awaken in the middle of the night?"