Not sure what ProM is getting at... but if my PC crashes, not too many people end up dead. If radar fails at a busy ATC Unit it's the controllers who are at the sharp end and have to pick up the pieces and prevent people from getting dead, not the whizz-kids who designed the gear. I've been there, got the tee-shirt and eaten the stew!
It might happen once in a lifetime, but in that brief 5-10 minutes the controllers earn their whole life's salary, just a pilot earns his when he has a major malfunction of his aeroplane.
Trouble is it was always so difficult to convey this to the engineering chasps, for whom I had incredibly high regard.