I've only seen a handful of sites do this. Developers inclined to respect Do Not Track seem less likely to add tracking anyway, in which case you also don't need the banner.

Sure, shady surveillance-based businesses can still pilfer your information and sell it to illegitimate businesses regardless of the legality. But it being illegal will stop the vast majority of wanting-to-be-legitimate businesses from collecting it, and prevent the largest group of threat actors (insurance/credit/etc) from using it.

I was responding to this: "There's also nothing stopping a website from showing a cookie banner, getting a user who clicks on "no cookies" and tracking that user anyway". You seemed to be implying that since a website can technically ignore a user's (lack of) consent regardless, that the popups are unnecessary. But legally, the concept of consent is very significant.

The popup mechanism itself isn't designed for you. I do agree that honest businesses don't need "consent" nag walls, as nobody actually wants their personal information datamined as a feature. But the actual dynamic is that these businesses are trying to preserve the status quo of user surveillance by obtaining fig-leaf consent. And the "best" way to do this (from their perspective) is an obtrusive nag wall that makes it easier to submit rather than reject (whether by accident or through attrition).

So nag walls are just a similar user-hostile solution just like surveillance based advertising itself. And the main way such malicious compliance will go away is further enforcement.

Depends on what legislation the website is hosted and/or the company is ? Not a layer, just trying to learn.