We're being compensated for being available (more on weekends and holidays) and get additional compensation for every 30 minutes incident response. Two incidents in one night? Twice the money. Additionally, we are required to work less the next day (we're also required by law to have at least eight hours of free time between two work days. So if you get an incident seven hours after you got off work? Congrats, you now have to wait eight hours before you can start working. This is of course very annoying, so nobody does that)

I'm not even sure if doing on-call duty without compensation is legal in my country.

In the past, there were some cases of "fake" incidents, but the amount of documentation makes sure that the company is able to crack down on this.