Not everybody own $4k monitors, so automatic brightness isn’t always available.

Regardless though, due to the design inconsistencies of the system, one screen is too bright that causes to reduce the brightness and another one uses literally 1/1,000,000 contrast difference between tabs to distinguish the active one, so it’s impossible to get a base brightness correct.

I’m using a MacBook Pro M4 and as I move around the house, automatic brightness either tries to blind me despite I’ve been in a dark room for a minute, or simply refuses to turn the brightness up when the sun is shining down into the room. It’s certainly designed for a certain environment, but not definitely a home.