> But in many cases, you could just click "reject" and the banner would also disappear...

Oftentimes the reject flow is substantially more annoying than the accept flow. I click reject myself when it's an option, but I can absolutely understand how people might get conditioned to click accept when clicking reject might result in more popups.

A lot of UK sites (Reach local news stuff) now explicitly say take cookies or pay, which tbh I always thought was illegal.