I think it’s important to be skeptical towards legislation as a solution to these things. The EU/UK cookie law is a cautionary tale, for example. After all that talk we ended up with a law that (effectively) mandates a boilerplate nag screens and no change in behaviour. Even if it had clearer language to distinguish allowable-illegal cookie use, it would still be very difficult to enforce.
I don’t mean to say legislation has no part to play. Just saying that the politician outrage to legislation sausage factory has produced some duds in this area. I wouldn’t count on a solution coming from this direction.
Speaking of enforcement… Most countries have an advertising standards authority. They create the rules and such. If an ad is (for example) a blatant lie, they can call up the Press/TV/Radio station and get the ad removed. Online, it’s not obvious what authority they have, or how they would enforce that authority at all.
Where advertising standards are still not broken is regulated industries. If a locally regulated bank advertises “one weird trick to double your savings,” the advertising standards people can go to the regulator. They have a number to call, genuine threats to make. ..enough to promote self policing.
Online, even reputable newspapers allow shockingly crappy ads. Sleazy data collection, snake oils, fake products, click farms, scams even fake news (ironically). Real shyster stuff.
This is on the visible end of the online advertising stick, the ad content itself. We already have legislation and a custom of rules. Still, enforcement is nonexistent. Dealing with the unseen data collection end of this stick is even harder.