The problem is that the more people know a secret the less likely it is to stay secret. I don't want the people I know to be able to download a profile about my from their local data broker. Even if my car company doesn't sell my data (which they probably will) one of the companies that do know it will eventually leak it and it will be slurped up and be made available to people that I don't want it available to.

Now you are arguing separate issues. There are three concerns here: data collection, data brokering, and data security. Your complaint is about the latter two. Addressing the data collection would certainly address the other two, but if those are the concerns why shouldn't we make laws focusing on them rather than the collection?

In the case of Target, they might mail your pregnant teenage daughter a flier for newborn items before she's told you the news.

https://www.nytimes.com/2012/02/19/magazine/shopping-habits....

Unfortunately it can also matter if your boss knows. Or the company you’re interviewing with. It shouldn’t matter (and would be illegal if it could be proven), but it matters.