The key difference here, though, is that all of those electronics are integrated into, and do not break the path of, the absolutely-must-work hydraulic path.

Throttle-by-wire is a different beast entirely. If you step on the gas and don't go, that's usually very annoying, and depending on circumstances could be dangerous. But if you step on the brakes and don't stop, that's pretty much a guaranteed wreck right there.