In the 1960s, Republic Steel used literal lockouts--the person working on the machine locked it, and had the only key.
It's been standard in the Australian and Canadian mining industry that long and still today - if several people are working on a machine (crusher, screen, stacker, etc) then they all have seperate keys to seperate padlocks that all lock a "gang plate" that scissors into the main power switch and prevents power on until all padlocks removed and gang plate removed.
Employee deaths should always be calculated under a standard calculus: $1,000,000 for a death, by default, with more based on how egregious the death was. If the company clearly ignored safety procedures, blame doesn’t even need to be assigned to any one person - double the amount can be extracted from the company.
Hit them right where it hurts the most. Hit them right in the profits. Because in the end, that is the only thing capitalism knows, or cares about.
You would be surprised to see how many people try to bypass safety measures just because they think it's tedious and too much work.
I've seen people do unsafe things which were against company regulations even though there was plenty of time to do it "the right way". If the company would have found out they would at the very least have received a written warning.