Industry, in this case, didn't even try to self-regulate, so a series of directives with gradually more teeth were passed over the last 20-odd years.
The problem in this context is identifying adtech as the industry rather than the adversary. It's like identifying a problem with spam and then asking the spammers to self-regulate. It's misapprehending the nature of the problem.
So then you say the spammers wouldn't self-regulate by not spamming so we're going to regulate email. Everybody hire a lawyer if you want to use email. And then the spammers still give you the finger because the internet spans the globe and they just set up in countries that won't enforce your rules, and the rules increase costs on everybody else.
What we need here are technical solutions. Browsers that resist tracking and fingerprinting. Technology to resist correlation attacks. The dissolution of unitary identity systems. More software that runs on your machine and not the adversary's machine. Make tracking too hard and there is no more tracking industry.
The thing most needed there is funding. There is profit in tracking and not so much profit in anti-tracking, so if you want anti-tracking then provide money for it. And for goodness sake stop passing laws against anti-tracking measures.
We can do better! Public education campaigns and support for alternatives for starters. The "they didn't fix the issues, so new laws will fix their issues" is myopic at the least, and potentially harmful if it doesn't fix the issues either.
You can educate me about green energy all you want, but if all the power providers I can switch to are burning coal, you're just wasting your time and money.
Passing laws is the opposite of myopic behaviour. To put it bluntly - theft is outlawed, not something we discourage solely through, uh, education campaigns.
Actually more than that, but I'm just using one of the shorter timelines involved.
So if the rather hands-off approach didn't work, campaigns didn't work, capitalism didn't work because it was always on the side of violating privacy? Well there comes the hammer.