First of all there is no comparison between car and aviation safety systems. And in aviation, many systems have both an electric and a hydraulically system so t

First of all there is no comparison between car and aviation safety systems. And in aviation, many systems have both an electric and a hydraulically system so that they don’t share dependencies. Second, if this is intended for gasoline/diesel vehicles, then you need two power systems as well. If you lose your alternator on the freeway and don’t notice, or are very far from a safe place to stop, and you drive the car on the battery until it dies, it’s going to slam on the brakes. In some scenarios that’s a safe default. In many scenarios, it’s the wrong thing to do.