The phrase itself is the problem. “Umpire’s call” sounds like a deference, a polite refusal to overrule a colleague. In practice it is a statistical threshold, applied by a ball-tracking model that nobody in the crowd can see.
The result is that identical deliveries can produce different outcomes depending on whether the batter is given out or not out on the field. The technology is doing exactly what it was designed to do. The language is letting it down.
A modest proposal: tell the crowd the number. Show the percentage of the ball that is hitting the stumps. Let people argue about the threshold instead of the moon phase.
It will not end the debate. It might make it more honest.