Technology: what does fail-safe mean?

Self-tutoring about technology: the tutor mentions the idea of fail-safe.

My understanding of fail-safe is that, if a system within a larger piece of equipment fails, the system that has failed defaults to the most benign state possible. Yet, what that means might be confusing.

In a car, for instance, what if the anti-lock brake system fails? Well, the car’s brakes continue to work, just without the ABS feature. That’s fail-safe: the car’s brakes continue to work viably.

What about electronics? In that realm, fail-safe will sometimes mean it goes to a state that makes it obvious a failure has happened (or is imminent), since not knowing it’s failed might be the greatest danger. A smoke detector might be an example: the models I’ve known start to beep when the battery gets low. You can’t ignore the device, so have to change its battery.

Source:

YT: Scotty Kilmer: “ABS Light Stays On, What To Do?”