Comment by samus

> No it's not. There are plenty of things that can't be 100% reliable no matter how well they're made. A perfect bridge is still going to break down and eventually fall apart. The best possible motion-activated light is going to have false positives and false negatives because the real world is messy. Light bulbs will burn out no matter how much care and effort goes into them.

All these failure modes are known and predicable, at least statistically