Do you understand the lock on your house's front door? Have you inspected every mechanical element to ensure it cannot be compromised? Do you routinely check it for tampering?
Yes. No. And No. It's a dopey comparison, really, but alright, let's play along. A common lockset works on centuries old, well-known principles. It's easy to understand. I know exactly how it can be compromised while appearing to function normally. I don't bother to take it apart and see if it's had it's been set up for a second key (commonly called a master key) because the risk is not worth the hassle. Now, if I had something that I wanted to hide from those who would like to see it, copy it, whatever, without my knowledge, it would a different story. Especially if the lock was the thing protecting my stuff from such a compromise. Hint: your front door lock is not the weak link. But let's say I don't have the skill and ability to examine my own lock. My only recourse is to "trust a locksmith", but not just any locksmith. That industry guards it's integrity and reputation with a unique zeal, and for good reason. That's rather like the open source community that has more than a few bright minds who love nothing better than the challenge of finding weak links in things like encryption technology. In other words, I wouldn't let Microsoft test my locks either because they have not done what they need to do to earn the trust of their peers in the locksmith trade.