It doesn't matter at all, because that isn't their goal/concern. This is, in all likelihood, political hoodwinking to subvert and circumvent the Second Amendment restrictions, and various other laws and court decisions, which limit what the government can do with respect to gun restrictions. There are restrictions on the government with respect to infringing on the RKBA, which in recent decades has been seeing a lot of support contrary to gun control activist concerns. If these matters are seen as issues of "private business", then there aren't any of those pesky restrictions to be concerned about. The question is, in the long term, are we going to be able to tie these activities into government influence under threats for the purpose of political power manipulations and be able to leverage that for protection of our rights and liberties. Now...why does this matter? Lots of reasons. For one, credit card tracking is a way of compiling a searchable database of who buys what, when, and how much. Outside of being a defacto registry, it's also a veritable font of information dedicated specifically to tracking civilian records related to the Second Amendment. So...why the push for this particular method of tracking information? There has been a gravitation, even a push, to move the entire economy towards a cashless one. A cashless economy means, quite literally, EVERYTHING a person does with finances is trackable BY DEFINITION. Right down to the last cent. All income. All expenditures. All travels. Who people interact with. Everything. Tying more things to financial databases means an ever growing potential for abuse as a data mine.