It wouldn’t matter… just tell the user to close and open the lid before pressing enter again, and get the maximum (or minimum) value as the lid being close all the way.
Exactly my thought, but this might not be precise enough in low light conditions? So maybe best used as a fail safe (if camera is lit don't calibrate even if the user pressed confirmed)
It does actually perform a security function. The lid angle sensor is used to know when the device is open or closed, and when closed, it physically disconnects the microphone. If you were to be able to recalibrate it at any time, you would leave your device vulnerable to having the microphone enabled when the lid is closed. You can argue whether that justifies the practice, but it's not as simple as just burning the EEPROM serial number in that tells it to turn the display on or off. It defends the user against an attack vector.
From that perspective making it one-time programmable is not unreasonable.
Though it could be simpler if it was something like a magnet on the lid that activates a magnetic switch on the bottom part (and it would be harder to have a false negative result). But Apple is going to Apple
Yes, it could be done with a Hall effect sensor or something like they used to. The cool thing about this approach is they actually use a different angle to turn the screen off as you close the lid than they do for turning it on when you open the lid, to create a better experience. Since it is a security feature, then the "open" vs "closed" state should use the same source of truth. So it's a trade-off of complexity and experience.
Apple even makes a suitable one themselves... but the point is that a calibration procedure involves adjustment and measurement, and not merely reading some data from the sensor and writing it back. If Apple weren't deliberately trying to be hostile and sneaky, they would not have bothered with this roundabout, obfuscated process which no doubt increases their production cost too.
