Some jobs obviously require being on call.

If you need 24/7 coverage, you also need to pay those people to wait around on call. But just buzzing people at odd hours and demanding Just-in-Time employment puts a disproportionate tax on their unpaid time.

Medical staff will often have these extremely long - 20 to 30 hour - shifts because they want to maintain continuous care on a patient. But they also get paid for being active for that time frame. They don't just teleport to the hospital when an ambulance arrives and teleport away again as soon as the patient is stable. Professional Fire Departments keep people on call in rotation so there's always someone available in the event of an emergency. The volunteer system yields much worse results, as people holding down households and second jobs can't drop everything on short notice to rush halfway across town with ease.

there should be appropriate compensation naturally.

But that will cost money. And paying more money means keeping fewer profits.