> proper consent banner

It is also quite complex to integrate a third-party consent management platform in a compliant way; the tool itself is a script, but it somehow needs to preempt loading of any other scripts until the right consent is given (there's also an argument whether the CMP being third-party is itself a breach of "data minimization" when such functionality can trivially be done in-house, or at least self-hosting the script).

The majority of sites fail at this, which already breaches the GDPR since merely loading a third-party script discloses your IP address and browser fingerprint to them.

It's not a big deal in their case because their CMP is itself configured to be non-compliant, but if you want to be compliant with a third-party CMP it's likely the effort to integrate it properly would be just as much as just doing it in-house.