The big difference is as an owner you are fully in control of allocating your time, and so if out of hours workload is becoming too much, you can choose to not work on other things in favour of fixing that. In the corporate world, there's some manager who weighs up spending two weeks to properly fix an issue or automate a process vs just making their workers unhappy and doing something that will make the manager look good in the internal politics, and often will insist on the latter.
But that's the problem with being in a bad company no matter what. If it weren't on call it would be something else that that manager would be making you suffer through. That doesn't mean on-call as a concept is terrible or that it's uncompensated labor, it just means that bad managers are capable of screwing up your life with any tools that you give them.
Bad managers are hard to predict. Even if you like your manager now, there's nothing to say they can't be promoted/reassigned/quit and you get a new manager that sucks. On-call being a thing is easier to get an answer on ahead of time
But it's meaningless a signal for bad managers because basically everyone does on call in some form. That's what this whole discussion is about: how ubiquitous it is.
The only job I worked that didn't have a formal on-call rotation ended up with me unofficially on on-call, with the same expectations as though that had been set up up front: boss calls whenever he calls and expecting an answer, and I'm left deciding how badly I want this job. Turns out management there sucked and I ended up on on-call after all.
If you find a company that actually has a good story for why they're able to get away with no on call, that might be a good signal. But if they're out there I'd love to hear from them, because most people here are just speculating about better alternatives, not speaking from experience with ones that actually worked.