When I have seen this done, the amount is often inconsequential in relation to the amount of effort to be on-call. I don't love this incentive structure because the cost of being on-call is somewhat fixed up front. Needing to avoid being out of page coverage / availability and having a computer available is a high cost paid by the employee regardless of actual page-out workload. Paying for standby certainly helps, but I haven't seen standby pay match well with the perceived effort. Maybe some companies do this right, but higher negotiated upfront pay has appeared more effective in my experience.

I'm lucky though. I see recurring conversations about it on /r/devops and I'm aware not everyone is in the same situation. Some even wear it as a badge of honour that they improve reliability so they shouldn't be paid for things breaking. (Which I completely disagree with) But working after hours is working after hours - if it doesn't feel right, maybe you should have a conversation about it.

Where devops works is that there's shared call-out responsibility when things go wrong at 2am. It won't happen again because they'll take the time to fix things.

If management don't also share in the responsibility, it -might- will happen again because they won't allocate the time (and-a-half) to fix things.