A site that serves static content, with no logging in or advertising on it that uses its data internally without attaching any identity to it still needs to have a cookie banner.

It demonstrates to the rest of the world how to be compliant with the cookie consent. If there was a less intrusive way to do it, the EU sites aren't demonstrating how to do it that way but instead have chosen to use a cookie banner that shows up every browser session. Secondly, the law is written so that any cookie requires that banner. Store a language selection in a cookie (clientlanguage - Cookie holding the user’s language selection - First-party persistent cookie, 30 days) and you need that banner.

The cookie notice isn't the "fault" of the site that you're visiting. Minimal client side data storing in cookies that isn't tracking a user's identity requires the banner.

The GDPR's cookie consent was written far too broadly to the extent that any use of cookies - even if they don't track an identity - requires a cookie consent banner.

The result of the ubiquitous cookie banner is that every site has it and people ignore it. This sort of alert fatigue makes it so that when there's a site that is following the law and is giving excessive tracking cookies that people don't see it as any worse than a site that is persisting if you prefer dark mode across browser sessions.

Furthermore, since it is so common, people become blind to it. Often people will install extensions to dismiss the banner so that companies that sites that aren't presenting the banner for the tracking data appear exactly the same.

As the law is written, sites that scrupulously following the GDPR are providing coverage for those that are not while simultaneously annoying people with a banner that everyone clicks some form of "accept" (be it all or essential only) training people to blindly click "accept" banners that pop up whenever they see them and contributing to the spread of malware.