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?
You give company A your data for a service. They provide you that service. However, unknown to you they sell your data to company B to make a few bucks. You did not authorize this, you did not know about this, you don’t know who company B is, and you have no idea to what purpose company B will put your data to. Best to not have this happen by not giving the data to company A to begin with.
Or admire the glory of GDPR.