The ad companies do.
So the ATF does.
If you have paid for anything with a debit or credit card, there is an electronic record of what you bought. With some good algorithms, they know what you have better than you do .
And that my friend is infringing against my Second Amendment Rights.
If you have to ATM the cash you need for whatever it is. Or, save up some cash and go that route. But, like not having a ‘social media’ presence, buying with cash looks suspicious these days to some folks.
That’s a great point. The ATF don’t need to actually know what guns you have if it gets to the point of bans and confiscations. They merely know that you may have owned one at some point and there are a threat. No need for a warrant to know about purchasesat individual FFL’s, because your credit card data is easier to search.