I have been doing this for decades and continue to do so to this day. You are simply wrong. There's not a snowball's chance in hell that Apple does a full manual regression test of the OS prior to each release. It's automated. And if they aren't doing a full automated regression test, then they aren't adhering to the normal standard of care. It's as simple as that.
You keep talking about regression tests, showing that you're a software guy at a desk.
The golden rule for all types of real engineering is that all systems must be validated in a relevant environment across all possible use cases. That means handing the phone to a kid. You can't automate that. That is expensive.
That's why kids are getting around Apple's app restrictions. Kids are smarter than the engineers who thought they could automated test their way out.
That is "standard of care". Boeing should have tested the 737 MAX with real pilots drafted from developing nations. Instead they tested it with professional test pilots. 346 died.
Again, shows why software "engineers" are amateurs and why they fight tooth and nail against licensure and liability.