it's It's possible.
I've had brake failure before, and while the pedal doesn't instantly fail and just drop to the floor, when the brakes start to go, they go quickly.
My specific case was the wrong kind of brake pads put on my car. Braking in normal situations was just fine, but once I was in bumper to bumper traffic, the stop and go traffic got the brakes too hot. When that happened, the pedal was extremely soft--going almost halfway to the floor before pressure was felt, and the braking action was extremely weak. Another application of the brakes meant the pedal went even further down and braking action was even weaker. If I had not pulled over to the side of the road to let the brakes cool, it's likely the pedal would have gone all the way to the floor and a collision would have resulted.
Suffice to say that I took the car back to the brake shop the very next day and they put the right pads on--someone screwed up big time the first time--so brake failure was no longer an issue.
My point, still, is that the walls of a parking garage should be more than just a visible barrier, that they should be able to stop moving car at up to a certain speed.
Not very likely, I would say. Then again when my brakes failed, they seemed just fine up until that point.
