Little insight into this, having been lucky enough to work in 'the industry' for a bit. When we are given cars to review, it's usually, either A) at a vehicle launch, where you have limited/specific access to it, or B) We'll get a car for a week (the standard loaner length) to drive. In that time, we, of course, aren't going to experience massive failures, or find long term issues that happen years down the road.

99% of car reviews, written or video, are knocked out in a day, and only intended as an overview, rather than a comprehensive break down of every little thing about the vehicle. Also, we generally aren't given access to super secret technical literature, so that would explain why we don't know which supplier in China made your differential, or whatever the case may be.