There’s pretty much no practical difference between Visa knowing all this stuff and the government knowing it. All Visa’s data is at most one subpoena away and that’s the optimistic scenario.

Of course there is a difference the other way. With a government run payment system only the government knows it. Not the government and some for-profit corporation.

And maybe even some other government which was an ally until a new old president is elected.

You cannot seriously believe that. Visa or any other private card processing company would actively seek to exploit it for its financial gains within the limits of the rules. The central bank (which is not "the governmentTM") would use the data to make sure the system is functioning properly or some other public policy goal. That's all the difference in the world.

> Is it much more worrying than having Visa being able to do that?

Yes, of course it is. How could anybody think otherwise? What is the worst thing Visa can do and what is the worst thing Visa has done? What is the worst thing the government can do and what is the worst thing the government has done?

Visa has to respect whatever laws apply in the country they operate in. So if the police want Visa info on whoever, provided that a legal framework cover this issue, Visa has to give it. It makes 0 difference if the payment system is government-operated or not. In any democratic country, the police would need the approval of a judge whether the service is public or a private company. And in dictatorship, the government will get the data or ban you from doing business in the country anyway.

I can think of at least one difference. If the government wants to lie about credit card transactions, Visa has to go along with it.

If Visa has it, the government simply needs to ask for it. There's a difference, but it's not much of one.

Sell your data to interested 3rd parties? Because anything else a government can do through their own systems they can require Visa to do as well, so seems like Visa with a profit motive has the potential to misuse the data even more than a government.

You could always just use cash then Visa wouldn't know.

Yes, it is more worrying. But indeed both are bad