In can only be effectively solved by introducing accessible controls in browser, available out of the box. Extensions are insufficient because most average users are not educated enough and this is not going to change anytime soon.

Also, the extensions I've seen have not so great usability. For example, I don't know any extension for Chrome, which would say "This page attempts to set you a cookie (details). Accept?" after login form submission (but not bother me with ordinary page views, 3rd party domains and other typical tracking/analytics stuff).

From my understanding of RFCs, cookies are offered, not forcibly set. User agents may store them or may discard them at their sole discretion. If there are concerns (there certainly are) about too lax cookie acceptance policies in popular UAs, it's UAs, not sites are the ones that should be fixed.

That's assuming that users want to learn in the first place, and dont' tune out the moment anything remotely technical hits their ears.

what wuld those extenions be?