Spent years taking oncall shifts. Nah, it really isn't. The two things I couldn't do were see a movie and go hike.
Otherwise life as normal. Laptop in the car, 4g hotspot on my phone. Only actually had to fix an issue remotely a few times (once with only my phone in a restaurant after a martial arts class).
Hospitals are probably one of the places uses on-call the most. A nurse or surgeon on-call doesn't sit around the hospital (at least not where I am from). They sit at home watching TV or eating dinner with friends, knowing that if there is an emergency, they have to go to work.
So they are paid for being available at a diminished rate, and if their availability is needed, then they are paid overtime.
Absurd analogy. My point is that I think it’s fair to pay less than regular hour pay when you are “waiting to work”. I also think it’s fair to pay more than regular hour pay when you are working outside of regular working hours.