[Someone]

Whether having multiple sensors guarantees redundancy depends on what they are hooked up to, and how.

If the software they are connected to doesn't know what to do when the camera fails or starts sending bogus data or even to detect that it happens you still may have a lidar, radar, etc. but it doesn't make the system fail-safe.

[hsjoberg]

Nope doesn't make it fail-safe at all and I don't think that is very hard to accomplish. What can be accomplished is fail-operational, if one sensors goes down using other sensors the car can navigate it-self to safety.