Earnhardt died from blunt force trauma to the head, most certainty would not have happend in a COT, but i think thats irrelevant anyhow. Whether it was Earnhardts own fault for being a bit careless is debatable, cared more about winning and being comfortable in his car he knew the risks, if he had chosen to wear a hans he may have lived, but thats also why now safety equipment inspections are frequent and the hans is now required.
Watch a driver crash in a COT these days, they can smash and flip into a wall, if they show the incar the driver hardly moves an inch