It's a very elaborate way of saying "writing correct software is hard". You know what's also hard to do correctly? Designing airplanes. Building skyscrapers...

It's a very elaborate way of saying "writing correct software is hard". You know what's also hard to do correctly? Designing airplanes. Building skyscrapers... the sheer volume of man-hours spent pouring over every minute detail of them, incorporating lessons learned from every failure that's ever happened in the field, amount to a very very high success rate. It's not only hard, but the cost/benefit (or the large penalties of catastrophic failure) works out so that it's worth it to go to that amount of effort. The same amount of effort doesn't go into building a backyard garden shed. I'll grant that we've gotten to the point where the cost/benefit analysis demands that we go to that amount of effort in critical situations.