Thankfully I have not, ever. But accepting your word, my words to describe such practices would be callous disregard to everything we believe, know and accept as safety. Yes you were lucky, but so were all those innocents sitting behind you in complete ignorance of the state of affairs up at the front end. Sort of thing nightmares are made of.
The only way to put a stop to this sort of practice is to put the guy who is at the very top of the food chain behind bars, and to do so not after a catastrophic tragedy, but way before, when a whistle blower with the full weight and authority of the law and without any fear of loss of his meal voucher, can stand up in a court of law and point the finger in the right direction.
Regrettably, even if this may have been the case in this instance, there could be no way to prove it, as they say beyond a shadow of a doubt. Those poor fellas have zonked out permanently.