You should consider reading the article.

Really truly hate agreeing with brookings, but they are right here.

I find it interesting where the line between freedom and acceptable government intervention seems to be for many people. There must be an aspect of “what do I have to worry about” that doesn’t kick in until people explicitly see what they have to worry about looming.

It's the classic "I have nothing to hide" argument. Which immediately breaks down when you realize that, with enough information about someone, you can implicate them in something illegal. A case can be built against them, a narrative spun, and an innocent person spending their lives locked up. This happens constantly in the US judicial system, though I believe it is often unintentional, just human bias doing it's thing.

I've read the article, and it addresses the point vaguely at best:

"The standard argument in favor of unfettered government purchases of private data is that such data is commercially available, and so anyone should be able to purchase it, including government officers."

Agreed.

"... while government officials can generally purchase items available to the public without constitutional restriction, sensitive private data about cell phone users isn’t actually available to the public."

What? I may be misunderstanding, but this looks like a deliberate attempt to conflate two concerns: publicly available data for sale and sensitive private data. I don't see any argument here against the government buying publicly available data.

Just because it is for sale, doesn’t mean it’s for sale to just about anyone - a lot of the brokers that collate, match, and enrich this data choose to only sell their product to government agencies.

Because it’s “on the market” it’s deemed “public”, but that market only is open to governments.

You should consider reading the rules

Apologies. Not my intention to be rude.