It's the odds. I keep coming back to the odds.
If antilock brakes just let go one time out of ten thousand, globally? Tens of millions of accidents every day.
A pacemaker fails one time out of a million? 100bpm average heartbeat times 10,080 minutes and you're dead in a week.
A generation of austerity politics was inflicted on the world by a fucking excel mistake, the famous Reinhart-Rogoff Error.
A just, humane society won't tolerate those failure rates in load-bearing software. We can't.