> even to know whether they've visited the site before
So uh, don't do that.
You don't need to notify if you use cookies for required functionality like login sessions or remembering a functional setting.
If you're tracking whether they're returning or not your activity is exactly the kind of behaviour the rule is covering because, in legal terms, it's skeezy as fuck.
> You don't need to notify if you use cookies for required functionality like login sessions or remembering a functional setting
Nobody wants to be the EU test case on precisely how "required functionality" is defined. Regardless of what the plaintext of the law says, it should be self-evident that companies will be more conservative than that, especially when the cost is as low as adding one cooke banner and tracking one preference.
It's a site where they log in and we store a cookie.