It isn't perfect but it's so much better than it used to be. Mobile drivers are still a problem, and part of the problem is that they passed their conformance

It isn't perfect but it's so much better than it used to be. Mobile drivers are still a problem, and part of the problem is that they passed their conformance tests years ago, and the test suite has improved a lot since then. But it's a giant surface area to test, it is not perfect. But still better than what we had 10 years ago.