In my experience, most people that have semi or full decision-making control over this kind of thing have absolutely no idea if they even need cookie consent banners. They just fall for the marketing speak of every single SAAS product that sells cookie-consent/GDPR stuff and err on the side of caution. No one wants to be the guy that says: "hey, we're only logging X, Y and not Z. And GDPR says we need consent only if we log Z, so therefore we don't need cookie consent." For starters, they need a lawyer to tell them it's "A OK" to do it this way, and secondly it's plain old cheaper and a lot less political capital to just go with the herd on this. The cost of the banner is off-loaded outside of the company and, for the time being, the users don't seem to mind or care.

This is why half the web has cookie-consent banners. No amount of developers who know the details screaming up the ladder will fix this. The emergent behavior put in place by the legal profession and corporate politics favors the SAAS companies that sell GDPR cookie banner products and libraries. Even if they're in the right, there is a greater-than-zero percent chance that if they do the wrong thing they'll go to court or be forced to defend themselves. And even then if it's successful, the lawyers still need to be paid, and the company will look at "that fucking moron Joe from the website department" which caused all their hassles and countless hours of productivity as a result of being a "smart ass".