I'm about to go all Karen managerial on yo ass.
It has everything to do with the manufacturer. The idiot on the assembly line is part of the manufacturing process. Rivian failed to close a hole in their process to prevent this sort of hu an error from happening. The same goes for GM in your steering wheel nut scenario. Can the problem be tracked down to one guy? Probably, but it won't be their job to fix it. Rivian will have to be the one to discipline/sack that employee and rewrite the process to prevent future fuck ups. I deal with this shit every day, and it sucks because the real fix is almost a paradox. Human error will always be present. Yet, we're supposed to eliminate it... as cheaply... and safely... and as high of quality... as possible. Automation helps, but that comes with a lot of red tape.
I'm just getting vibes from others here that a loose nut is not a big deal when it is. Luckily for Rivian, the recall is as simple as torquing that nut and shouldn't involve much if any disassembly of the vehicle.