It's called dark patterns and malicious compliance . The annoying banners in particular, were designed by IAB Tech Lab, which is an industry front for adtech/martech companies.

Oncehub removed tracking cookies from some of their meeting invite pages in the EU and stopped showing a banner, because they thought it looked offputting.

They got a few support tickets from people who thought they were still tracking, but just removed the banner.

It's (at least in some cases) malice, not stupidity.

By putting cookie banners everywhere and pretending that they are a requirement of the GDPR, the owners of the websites (or of the tracking systems attached to those websites) (1) provide an opportunity for people to say "yes" to tracking they would almost certainly actually prefer not to happen, and (2) inflict an annoyance on people and blame it on the GDPR.

The result: huge numbers of people think that the GDPR is a stupid law whose main effect is to produce unnecessary cookie banners, and argue against any other legislation that looks like it, and resent the organization responsible for it.

Which reduces the likely future amount of legislation that might get in the way of extracting the maximum in profit by spying on people and selling their personal information to advertisers.

Which is ... not a stupid thing to do, if you are in the business of spying on people and selling their personal information to advertisers.