I don't think most people here understand how labour laws work. "On call" is a well defined concept and IME universally allowed. Any Western jurisidictions DOES require you to pay someone when they actually get called. If it's overtime or not follows the regular rules for how that's calculated, same with time off and maximum work periods.

What we're discussing here is how companies encourage and reward (or don't) for the inconvenience and impact of staying near your computer, not going out of town, or being woken up in the middle of the night. None are going to pay you time and a half on regular work commitments because you might get called.

Jobs like a fire fighter are completely different. They work a scheduled shift and either respond to calls OR do other work during that time. They're not really on-call as much as prioritizing work. They also don't get 1.5x for their regular scheduled work.