if you were driving your car along a straight road with the wheel pointing forward - and suddenly it veered off to the left or right unexpectedly so you have to correct it - is that your concept of a working car?
I really hope you don't work in the automotive or aeronautic industries. "Sorry passengers we've unexpectedly descended to 100 feet due to a beta firmware in our plane and are about to crash but hey we can't get it right all the time huh?"
These horrible things happen all the time in the automotive industry and, mercifully, less often in the aircraft industry. Even when lives are at stake coding and mechanical errors occur.
The Phantom is just a big toy that, as far as I know, doesn't automatically endanger human life when it goes cattywampus. To me it's a bloody miracle these things are as bulletproof as they are.
You want perfection? Seek a religion. In my estimation, It is too much to ask from a flying computer manufacturing company.