I have always seen the cookie banner as a sort of punishment to the public for daring to have demanded better treatment.

“Oh you want consent involved in this interaction? Then we’ll annoy you about it constantly instead of respecting the intent of the regulation.”

I’m certain it’s often just the California “literally everything is known to cause cancer” problem.

It’s simplest just to put the bullshit everywhere and the dipshit bureaucrats will leave everyone alone.