It's not obvious how an errant piece of large, heavy, machinery could kill someone? There's a software bug in one of my tractors (not John Deere) where it won'

It's not obvious how an errant piece of large, heavy, machinery could kill someone? There's a software bug in one of my tractors (not John Deere) where it won't always immediately disengage the clutch when put in gear (yes, even the transmission is fully computerized). One time during a long day in the field I accidentally left it in gear, not noticing because the tractor was at a full stop with no signs of moving. A few minutes after I got out of the cab it decided to kick in. Luckily it was in a low gear and I was able to safely get it stopped, but it's easy to see how that could have ended up tragic. While that one was ultimately my error, without that bug it wouldn't have been an issue in the first place. I'm sure you can come up with arguments as to why that software shouldn't exist – although I have to say it's wonderful when it works – but it's easy to see why bugs can be dangerous.