Trouble with bike shops

[uforgot]

What I don't quite get is... Brakes are pretty simple. I can't see how badly put together they can be or messed up - as long as they're not rubbing the tire when you're braking, and your braking is working...And you have to make sure they're screwed on tightly I can't see how the shops are accusing each other of doing a bad job on the brakes. (if they were rubbing, you clamp down on the brakes hard, it centers the brakes - and then you tighten them with an allen wrench there)

That stuck me odd, also! How can you totally screw up the brakes?