It's a distinction. Private companies are partnering with the government to take away personal liberty.

We should ban the government from accessing data gathered by private companies by default, perhaps. I need to mull on it.

The point is that "who gathers it" should be irrelevant.

The government shouldn't be able to buy data that would be unconstitutional or unlawful for them to gather themselves.

On the other hand if a company is just aggregating something benign like weather data, there's no need to bar the government from buying that instead of building it themselves.

I also personally think there are some private collections we should ban, or put in place limitations on how it can be used, in the interest of general privacy.

That is trickier to decide on and surely there's room to debate.