(Besides, macOS and Windows do let you tweak the trust store from their respective GUIs. There’s nothing stopping you from doing so.)
See also, cookie consent banners.
While dialogue fatigue is true, browsers can take care of offloading the cookie dialogues if there were a standard for it.
Doing what's necessary for privacy is no excuse to throw bad UI at a user. There has to be a way to customize our transit security and subsequently privacy. It's a step in the right direction.
Corporate users do not have a control over this, nor will people where governments try to propose a law forcing people to accept crony CAs to the trusted list.
If you’re trying to circumvent your corporate laptop’s MITM, you’re playing a lost game. It’s also a game that has nothing to do with ordinary users on ordinary, non-work computers.