You don't really need a web dev to add a cookie banner these days, but you probably still want one to build the actual site (unless it's simple enough to be fully site-as-a-service, in which case there is really no webdev at all).

Be it the EU for regulating disclosure and consent requirements, users for being "lazy" and usually just accepting all, or the webdev for not staking their livelihood on denying the banner - I'm sure they'll all get blamed before someone sees the ones actually demanding it be done can be the problem.