> Legally-required cookie banner > PostHog.com doesn't use third-party cookies, only a single in-house cookie You're legally required to let me opt out of that cookie. Unless it's essential to the site functionality, in which case you don't need the banner at all.
Considering they have a login system, I'm going to guess that the cookie includes your login (probably in JWT form), which automatically makes it essential to site functionality. Which means the banner is there just because if it was absent, someone would say "Hey, where's the cookie banner?" In other words, it's not actually legally required in their case, but it's practically required, because it lets everyone know…
Your "logic" is baffling