Why is it bad to go through metal detectors to go to school?

I go through a metal detector when I go into work.

I go through a metal detector when I enter a courthouse.

I go through a metal detector when I go into the Capitol.

None of these things detracts from the gravitas of those places, and none of them makes any of those places feel less safe.

Especially when the alternatives include impinging on fundamental rights or forcing kids to go through sometimes horrifying active shooter drills, I have a hard time understanding the objection to metal detectors.