Though again, not ideal IMO; based on skimming those policies, I think they could've set it up so consent popup only shows in specific situations that trigger the need for it. That, and I don't get why they use (a minimal build of) Google Analytics, and let that data fly over to the US (which they explicitly acknowledge). That's just lazy.
From a web designer's perspective if its a question of "do I do it the way that europa.eu does it, or try to pioneer some new other-than-banner approach to GDPR compliance - what is the risk to me or my company that I'm doing it wrong that that the EU will come down and fine me?
Maintaining the same interface as europa.eu is the least risky approach and so everyone does it that way.
If one wants to say "the GDPR doesn't mandate cookie banners" then it should be the GDPR site in europa.eu that demonstrates how that can be done with other styles of cookie consent.
Until then, it is perfectly fair and reasonable to assert that the GDPR requires it because the GDPR site itself uses it and companies that haven't done it that way have gotten fined.
https://european-union.europa.eu/index_en
https://gdpr.eu
If cookie banners were not designed to be required... why does the EU pages themselves use them?