I am of the mindset that a healthy team doesn't need an on call. Group chats, tight relationships, etc. usually mean someone is free just based on the odds to handle a true emergency. If you have so few people that the ship can't run, but you're not in a startup environment that justifies having so few people, that is your real problem.

An average company with engineers who don't hate their job, staffed adequately, it should be a stars align kind of scenario where you can't get someone on a weekend. It's a simple matter of probability, and if that probability looks grim, either A. you're understaffed, or B, your staff is underengaged.

I have fixed customer outages on my phone out having a good time more than once. Usually with another engineer happy to help. Not just at one company. If you need an on call rotation, your culture sucks. I'm not advocating that people live to work, I'm advocating that people work at places where people enjoy working with their peers and their product enough that an occasional blip isn't a big deal. With the right infrastructure and the right people you should have this.