If you as a developer are tasked with understanding this, you take the time to read the actual rules and then you misunderstand it, you are incompetent. But this is not what generally happens. Folks don't read, just yolo some terrible explanation off of SO and then complain when someone tells them they are not compliant. That's laziness. Those are the only reasons for noncompliance, outside of actual malice.

It can be cheaper to misunderstand it. So long as risk of getting fined is low, and the fines aren't higher than they are, you aren't really tasked with being compliant. You are given a task to implement something in compliance but what that means is as compliant as possible while still making sure the business survives, possibly even on the same business model. That latter part isn't explicitly given to a developer in the instructions - but it's going to be made clear that if you don't want to put up the minimum-effort cookie wall, there is someone else that can do that job.

This is why we need a law that people actually fear to the point where they would rather switch off the lights and take down the sign, than try to put up an off the shelf cookie wall that can be configured to have an "Accept all" button.

Terrible take. If breaking the law to make money is how you operate, you're not a company. You're a criminal cartel.

That’s how all these sites operate now. It’s cheaper to keep operating in violation than shutting down. That’s what should change.

Why?

maybe developers beed some adjusting to make compliance numbers higher.

Because GDPR has been around for a few years and its still unmanageable. Laws need to be realistic to make compliance easy and widespread. Maybe there needs to be resources for training or something. There are lots of things you can tweak while still getting the benefits.

Compliance is easy and manageable, for the most part. It's just that companies want to still do the things the law is trying to disincentivize, and want to put as many dark patterns as they can in the way of users avoiding it. So the "unmanageable" part is trying to figure out how close you can come to breaking the law without being blatant.