Comment by PaulDavisThe1st

One cause for lack of productivity gains is Baumol's cost disease, which generally affects organizations involving N different people (for N>1) where for one or more reasons N cannot be meaningfully reduced, if at all. Orchestras are the canonical example.

There's a variant of this, however, in activities that are done essentially by 1 person (as is true for most of the examples you mention in your last paragraph). You can improve their individual productivity - more pipes fixed, more joints welded, more patients well-attended to (*) - but in the end you cannot get rid of the individual doing the work in the way automated manufacturing has.

(*) even with a nurse though, this starts to break down for activities where time is a critical part of whatever is being done. Sometimes caring well for a person is primarily a matter of spending time with them, and this is certainly true for teaching as well. In such cases, you cannot make the person "more productive" no matter what technologies you might provide them with.