- Apple has practically unlimited money
- The company can afford the best of the planet's talent
- The companies business is ethical and therefore the top layer of talent hesitant to join ad-based companies pick Apple naturally
- The company is highly design driven, which means it's the perfectionists making most decisions (roughly speaking)
All this seems to have a cultural impact that optimizes for quality without much a/b testing.
They also make it challenging to switch teams internally, you basically compete for the same role an external candidate would, and you interview as if you were an external candidate.
All of that makes it very easy to get burnt out and so either you are someone bought into the "cult" of Apple and couldn't see yourself working anywhere else, or you peace-out once the rose-colored glasses come off.
Highly ethical ? They're China's lapdogs (Google left China). Also they're the ones who don't want to pay employees for the time they spend being searched, nor acknowledge when their platform or their customers have a virus.
Design-driven ? They're the ones with keyboards with a 30% failure rate and $500 repair cost. (They're PR and financials driven).
They certainly have unlimited money, and have shown they're not afraid to sue, and bully, or reward compliance.
That said, of the companies who market their ethics, Apple seems to actually _do_ more than most.