I've observed this in more than a few places — teams treating QA as the de-facto tester and gatekeeper that has to find all the bugs, while developers just writ

I've observed this in more than a few places — teams treating QA as the de-facto tester and gatekeeper that has to find all the bugs, while developers just write code to satisfy their interest in writing code, and not spending a lot of time testing it. I wonder if this is the case in Apple too, where developers just write something without a lot of testing before handover to QA, and QA is pressed for time and/or doesn't know enough to test it well before a release.