The substantial evidence is a dead body, which disproves your theory.
You probably think to O-Rings from the space shuttle Challenger were adequate, don't you? You know, they worked MOST of the time!
Not at all. When you have to use cattle prods, whips, or slingshots to motivate the animal to perform the amazing feat, then the 67 years of containment shows the confinment was adequate.
"You probably think to O-Rings from the space shuttle Challenger were adequate, don't you?"
No. They were not adequate.