We originally designed Radar so that bugs would be verified as closed by the person with most interest in seeing this happen: the tester assigned to that part of that project. Then management swooped in with an edict that bugs must be verified as closed by whomever originally reported them. This is a stupid idea, because it creates the perverse incentive that no one should report a problem if they are outside the team (because then you are committing to verify the fix, which just means more work for you that has nothing to do with any of your main responsibilities).
When I pointed out that the system would now discourage people on different teams from helping each other, the sponsoring director said "that's what pink slips are for." Direct quote. Soon after that I resigned from the design team.
Without reasonably skilled and principled leadership, you just don't get quality software. And "quality is everyone's job" is just an empty and childish slogan. Excellence is not transmitted through slogans and wishful thinking. You have to assign responsibility, provide resources and time (which means lowering velocity of new development), and follow-up.
The fundamental reason why it doesn't happen is the technology market is not efficient. Quality is, in fact, not as important as career testers wish it were. You can get away with doing terrible work and not lose your job. The fact that Apple pays no significant penalties for having buggy products insulates it from our slings and arrows.