If the site allows you to visit it, is it working incorrectly?
If a site works correctly, but would work even better with a cookie, is that cookie essential?
Obviously this isn't the way the lawmakers intended the law to be interpreted, but it is probably considered a valid interpretation of the law.
The banners are there for you to opt-in to your activity on the website and beyond to be tracked by a 3rd party, possibly across multiple other websites.
We do not need to discuss whether a cookie is essential, because it's a red herring. It's not about cookies, it's about behavioural tracking, it's about your browser activity being sent to 3rd parties, being collated and used to e.g. serve you advertisements to sell you shit.
The problem is that individuals and small businesses would rather interpret the law in a way that isn't going to get them in trouble, even if it is over-reaching. There has been a level of paranoia stirred up, caused by other companies interpreting the law badly.
It's like staying away from all bodies of water because someone sometime drowned while swimming in the sea. It's a vast overreaction, but it works.
In short, we have lots of armchair lawyers giving idiot-in-a-hurry interpretations, and everyone is doing it wrong because everyone is scared of doing it wrong.
It doesn't matter what the banners were intended for.
