What harm does public data have to you? Couldn’t one just ignore the ads? You can’t see anyone watching you, is public data good for public records? (I’m just curious). I know this sounds weird but is public data good for historical preservation and knowledge increasing the importance of the individual? And does public data lead to better products?
Well, also, bad things absolutely can happen right now, they just aren’t as obvious. People focus too much on how the government uses data to abuse people, not enough on how private companies can in opaque ways. Cambridge Analytica is an example of very bad things happening right now.
Also consider how the Supreme Court basically decided businesses discriminating against LGBT is acceptable. With how accessible user data is now, it would be trivial to put together a database of gay people, particularly same sex married couples, that businesses can check against. There’s also every reason to believe rulings like that will continue and new avenues of abuse will open up for private companies.