There isn't any way EU didn't knew this was possible and is a better choice. There already was DNT header that they can regulate. It also knew the harm to ad industry.
There isn't any rule that requires websites to use a cookie banner. Your required to obtain explicit consent before reading/setting any cookies that aren't strictly necessary. The web came up with the cookie banner.
Google could've implemented a consent API in Chrome, but they didn't. Guess why.
Google could've implemented a consent API in Chrome, but they didn't. Guess why.