Yeah On-call can vary greatly by company, although how On-call issues are handled can have a huge impact on your perception of a job.
At one previous employer, you were on a 2-week rotation for on-call.
But Every time you were on call, it was the same set of problems, always at the same inconvenient times (Mid sunday afternoon, random weekdays but always between 3-5AM, etc.) Admittedly often they were NOPs (Oh, alert came in, but when you check the system it's fine.)
But we didn't fix the false alarms. And we didn't fix the recurring real problems either; the Org's view was that was the entire purpose of the On-call person; that middle child you send to pay the loan shark not-quite enough because you don't care what happens to them.
At later employer, I actually had to deal with -more- on call issues, both in severity and frequency. And yet, I hate being on-call less, because at the very least when we find problems on-call the org puts a focus on fixing them.