Gotta say, I'm a blue collar who also builds sensitive machinery, have been doing so for six years now.

There is a VERY sharp divide in how well I consider myself to have mastered certain aspects of the job.

Someone fucking kill me: I'm doing this job for the first time and I'm having to spend ages sifting through our processes that may not be documented in enough detail to do the job perfectly. The job is legally safe because I'm following the rules but god I don't like it. Takes about three times as long as a 'normal' task.

This is fine: I've done the job enough to know how everything goes together, what torque to use where, and if there's anything I should really be doing that isn't in the instructions, or if there's an instruction mismatch.

Mastery: I can not only do the job, I actually understand the explicit purpose and function of everything I'm putting together on an intimate level, and can use my knowledge of that purpose and function to make god damn sure that what I'm putting out is top quality. As probably the least sensitive example of this, this is stuff like knowing that the particular brand of no-mixing-needed paint we use can sometimes develop a sediment layer of its' pigments on the bottom that requires you to mix it with a stick for the paint to perform properly, and that you can tell when the paint is experiencing this issue because it'll be off-colour due to the lack of pigment; and if you don't resolve this issue the paint won't adhere to surfaces correctly and is liable to flake off.

I've been doing this for six years and there are only a handful of aspects of my job I consider myself to have complete mastery over. I don't think I'm the best worker out there, not by a long shot, but to me the idea that you can just lose and replace your workforce when dealing with complicated machinery is about as stupid as the notion that AI can replicate the human mind (It can't unless you abandon the von-neumann computer design).