For example, for cookies, legally force, with the cookie (with a standard protocol), transmit of "intent", like cross-site tracking, whether it is used for advertisement or something else, whether it may be shared with third parties, etc. Then the browser would simply not accept cookies with intent the surfer disagrees with.
And then you get Facebook spending millions of dollars taking out full-page ads in newspapers telling people that you are an evil demon who kicks puppies and hates small businesses.
(Ever notice that when Facebook wants to reach the most people, and the most important people, it uses newspapers, rather than its own platform?)