Please provide documentation of this belief. I just spent a half hour looking for an article about the actual tech at that level and am still looking. This is the first I have heard that it is not where the pitch crosses the plate, and it is quite a claim to just throw out there with no support.
I did find this to clarify how the strike zone is set for each individual batter:
https://www.cbssports.com/mlb/news/robot-umpires-how-it-works-and-its-effect-on-players-and-managers-in-the-atlantic-league-plus-whats-to-come/
"TrackMan, or "robot ump," sits up above home plate (at all eight Atlantic League ballparks), and looks like a black box from afar. In reality, the box is a 3-D Doppler radar dish that analyzes each pitch thrown. Using a three-dimensional strike zone, TrackMan is able to calibrate each batters' size and stance, adjusting the strike zone accordingly. So, the system works so that it doesn't allow a 6-foot-7 player to have the same strike zone as a 5-foot-7 player."
......and this is really interesting, even if it is a couple years old:
https://www.bu.edu/articles/2019/mlb-umpires-strike-zone-accuracy/
"MLB Umpires Missed 34,294 Ball-Strike Calls in 2018.
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Graphing performance results also highlighted a natural divide—umpires with at least 20 years of experience made more incorrect calls than those with 10 years or less of experience. For 2018, Ted Barrett and Joe West were the top poor performers, making 495 and 512 incorrect home plate calls, for an average of 17.7 and 16.5 errors per game, respectively.
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MLB is simply ignoring valuable, available data. Despite the hard evidence, each season, MLB continues to keep questionable performers, some past their prime, on the job. The past three World Series were only the most recent examples. Game by game, season by season, poor-performing umpires remain on the field.
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It is unrealistic to assume that home-plate umpires, unassisted, can collectively achieve the accuracy rates increasingly demanded by the sports industry and deserving fans."