Just because there's a PR process in place doesn't mean that it's any good. At one place, we desperately avoided some sections of the code base because we didn't want to trigger a PR that would force us to interact with the team running that section. They were slow, obnoxious and power mad.
A PR is only as good as the person evaluating it. You can't even say reliably that it's better than nothing because sometimes it isn't.
No, Tesla use Pull Requests too. It’s fairly standard GitHub usage, at least within the org I worked at. They also GitHub actions, though obviously the build tools are non-standard.
GitHub cannot be used without pull requests. Git cannot be used without commits. Whether there is a code review process or everyone self approves is another question.
Are you saying at Tesla, GitHub can't be used without pull requests? You can for sure (obviously) just push to whatever branch you want for your GitHub hosted repository if that's your desire.