> when your next would-be employer or would-be landlord ... uses a data broker for "background checking"
Knowing an SSN (US Social Security Number) was used like a password by banks and all kinds of organizations, but not anymore. Things change, albeit slowly, when society acknowledges mistakes. All of your examples rely on the data buyer trusting its accuracy. If enough people pollute the data, then it'll have no value. The data brokers won't be able to sell it because society will know that its garbage.
The vast majority of the time, the people buying the data know it isn't 100% accurate and they also don't care. They're usually not looking at individuals, they're looking at large groups of people who (probably) meet whatever criteria they've set. If they get it wrong a bunch of times who cares as long as the other times it works. Better than chance is good enough for them.
Data brokers can always count on there being some people who are misled into thinking that their data is far more accurate than it is. They're trying to convince everyone right now that AI is the golden solution that makes them super trustworthy compared to their previous failings. Tomorrow it'll probably be "quantum something" or "super surveillance" or some other gimmick. They really don't have to care. They'll always be able to sell their stuff.
Data brokers will always have the police and the government buying up their data too because the government is happy to just suck up everything they can and will figure it all out later. They aren't concerned with accuracy either. That's how people get arrested for just riding their bike past houses that got robbed. They can make all the mistakes they want and it doesn't hurt them any, even when it's a huge problem for the people caught up by lazy policing.
I promise you that no browser add-on is going to collapse the targeted ad industry or bring an end to surveillance capitalism. Giving people more data to use against you is a bad idea.
Knowing an SSN (US Social Security Number) was used like a password by banks and all kinds of organizations, but not anymore. Things change, albeit slowly, when society acknowledges mistakes. All of your examples rely on the data buyer trusting its accuracy. If enough people pollute the data, then it'll have no value. The data brokers won't be able to sell it because society will know that its garbage.