What the technicians are there for isn't to operate the robots...they're supposed to analyze the performance of the robots constantly and summarize anomalies and flag them to the next shift. So a work shift might involve metrology, statistics, and communication skills; I wouldn't expect that skill set from any but the most exceptional US high school graduates, and those folks are bound for the university, not a job with 12-hour days wearing clean room suits and limited bathroom breaks.
Some of the more fussy processes like EUV require regular cleaning of excess tin in the machine as well to keep yield up. afaik it's a trade secret as to how this process works, but I know one of the big delays in rolling out EUV is that the cleaning process was hard, and that lead to a lot of downtime on the line. People on both side of the Pacific were able to make chips with EUV for a while, but they just couldn't make money while making them. TSMC cracked that nut, but I haven't read any articles describing exactly what their magic was to get the uptime so high. However, I suspect it might involve a platoon of PhD-level experts that also work like an F1 pit crew.
Anyways, the days of carrying boxes of wafers from machine to machine and pressing buttons are long gone. Everything that can be automated has been, what's left is debugging and servicing robots, and searching for early signs of degradation in an otherwise fully automated machine.
So, the real value of a highly trained technician in this case is they can look at bumps in the data and go "huh..." and flag it to management so that you don't have 80% of the fab full of trash wafers. In this situation, you want someone who actually understand the physics of the process going on inside the machine, and not just someone who is following an SOP. Any analysis that could be easily automated probably already has been.
Of course, you need even more highly skilled people to set up the robots in the first place, and that process also consumes hundreds if not thousands of engineers, depending on your schedule, scale and the complexity of the machines. A lot of that can be pushed back onto vendors, but you still need an on-site team who actually understands the physics to get your process yields up to several nines and hold it there with almost no downtime.