> > Programs can be very close to 100% reliable when made well. > This is a tautology.

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.

In any case, unless you assert that programs are never made well, then your own statement disproves your previous statement that the reliability of programs is "far from 100%."

Plenty of software is extremely reliable in practice. It's just easy to forget about it because good, reliable software tends to be invisible.

> 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