Process always falls down at some point, it's why we have bugs in the first place. The point of view that "obvious bugs should never happen" is pretty obviously

Process always falls down at some point, it's why we have bugs in the first place. The point of view that "obvious bugs should never happen" is pretty obviously broken, you just try to make them as rare as humanly possible. Besides, simple looking things from the outside can be maddeningly complex from the inside - for all we know this could be related to an obscure bug in their test framework marking it as passed when it isn't. Most of the time when people say "what a stupid mistake" they mean "that's a mistake I haven't made yet"