There is at least one big company out there, where every dev is part of what they call the "on call rotation" -- where being "on call" typically means being on pager duty -- without any special compensation for that. The only exemption is if you're working on a project that isn't yet in production. They tell you about it during their recruitment process and they communicate it very clearly: take it or leave it, there are no special cases. It sucks, but a lot of people take it anyway.
Yup. We're on call for a week at a time. Only compensation is the "privilege" of working from home on the Friday of the week we're on call. No extra pay, no comp time, nada. Luckily the number of calls is very low, maybe 1-2 per week.