[unabridged]

>It makes me think about all of the manhours that could have been saved if the law had instead required major browser vendors to include a feature enabled by default that would prompt the user before storing cookies.

You only need a disclaimer for a permanent cookie, which should only be used when you are logged into an account (and the disclaimer could just be part of the ToS when you create the account). I blame the websites for using permanent cookies when session cookies or no cookies would do the job.