I've spent a bunch of time in light manufacturing. In testing assemblies I've come to the conclusion that for ordinary stuff you just want to reduce the rate of 'bad product' below the rate of installer fuckups. If 9 times out of 10 the reason is failed it because someone fucked it up and 1 out of 10 is because you shipped a defective unit, no one cares.

You might go, well what about safety critical things. Well it's still true. Just at a much lower level of failure.