It is an utter failure but mostly because services try hard to turn it into a travesty and simultaneously manage to deceive their users by attributing blame for the annoying cookie warnings to regulators.
"We are required by law to show you this stupid warning because our site uses advanced features that need cookies to work. Without them, you couldn't even login! (OK)"
Which, of course, is utter bullshit. If you can stop this deception, things might actually work out as intended. Sites may rethink their need for personal data gathering if cookie warnings would have to look more like the following.
"We'd like to analyze your site usage for ad targeting and other things that make us some more money.
Do you agree we use cookies for that? (yes/no)
NOTE: Even if you disagree, standard site functionality like logins will continue to work unharmed."