Actually stamp down on the sites taking the piss. Without teeth, GDPR is useless, but so would any other toothless solution be.
Once one of the big players that don't do this and instead have it e.g. opt-out are actually fined, I suspect more sites will begin to behave correctly.
The problem with fines against Google (and Facebook, too) is that it's peanuts for them. They just factor this in the same category as "legal costs", and it never affects them even remotely.
If, and I say If, these gangsters ever get hit with major fines, and we get the simple yes/no option that a few pages have, then it will be better.
Right now, the ad industry (or should i say Mafia) is trying to actively circumvent this legislation
There would be ways to get control over this, but law is slow.
Pushing all this through the legal system will take some time but the watchdogs in different countries are not sitting idle.
[1] https://fil.forbrukerradet.no/wp-content/uploads/2018/06/201...
0: https://www.gdpreu.org/the-regulation/key-concepts/legitimat...