Every car I’ve driven with keyless ignition (which seems to be the standard now) refuses to lock if it detects the key inside the car, even if you try to do it manually by pressing the lock button, so hopefully this is a solved problem now.
I’ve honestly never heard of self-locking cars doors, that’s a crazy idea.
Some things make more sense with additional context. Like, Europe was on the PAL standard while Japan was on NTSC, so even if you put them both in the same region, they couldn’t watch each other’s discs, so the region code could be re-used without it actually conflicting.