Sure, certification does not ensure compliance. But it takes a VERY special culture for a company to truly meet requirements (ISO9001, AS9100, etc.) without being externally audited as a way of providing "incentive".
Just like operator self-inspection, it can work well, but it's not for everyone - or not for most.
Just like operator self-inspection, it can work well, but it's not for everyone - or not for most.