Grab
I take your point. Perhaps it would be better to point out that because of the flexibility modern the PLC offers, the system complexity of most things now is levels higher than before. You are right when you say that computer controlled cars hink out "not too often," but if it does happen, say, once a year on a component or system which used to offer graceful degradation in the past - well, I hope my point is made too.

I think today, making guns, or cars, or DVD players, designers who layer on the features and maybe ought to give a little more thought to the concept of "mean time between failure" of those components and the total impact on system reliability.

Mark