They’re just really good at taking the time to ship great stuff, that’s often in service of some greater vision that’s visible only to a small number of the leadership. Jobs set up the factory and it’s still churning out unmatched products. Every engineer there gets the last ounce of effort squeezed out them by WWDC by the system he set up. It would be even better if Jobs was still around of course, albeit with a tad more burnout.