Why not vote for some law limiting the government’s buying of this data? After all, I expect a say in how the government is run, so that seems like the appropriate path. I don’t see why I should expect a say in how AT&T is run. AT&T can’t raise an army, or enter my house, or shoot me.
You didn't purchase your lawmakers, the companies profiting from the bad laws did.
This is why they get their laws passed.
How exactly do I vote for such a law? We do not have a direct democracy, and I'm not aware of any viable political candidates that have this sort of thing as a part of their platform.