But how do you know it's cut to spec if you don't measure it?

Maybe someone bumped the fence aw while you were on a break, or the vibration of it caused the jig to get a bit out of alignment.

The basic point is that whether a human or some kind of automated process, probabilistic or not, is producing something you still need to check the result. And for code specifically, we've had deterministic ways of doing that for 20 years or so.