I must be missing your point.
We shouldn’t have brake-by-wire on cars because there is a potential for it to be damaged by incompetent personnel?
Isn’t that true of any critical part of your car already?
Except that by switching to eletric brakes, you run the risk of someone cutting the wires when they’re hooking up a big honking stereo system (that seem to be proliferating rapidly these days), which is unlikely to happen with a hydraulic brake system (and the brake fluid oozing out from underneath the car is a definite red flag that you’ve screwed something up, whereas you might not get a spectacular spark show or fire when you cut a wire). Generally, the only partof the electrical system people play with in their cars is the stereo system, the rest being too complicated for them. Lot of guys I knew in high school were decent mechanics when it came to fixing the mechanical parts of their cars, but when they installed their stereos, they cut the wrong wires, or hooked the radios up wrong, and either shorted out the stereo or other parts of their cars, and some times the damages to the other electrical components weren’t immediately obvious.