Technology

Personally, I think the easiest one is the US government refunds the tariffs to the company with the requirement that the company has to give it back because the company already has all that information

However, if We were to continue this hypothetical situation where the US is the initiator.

All they would need to do is make it so it's a hard requirement in order to get the tariff return that the companies provide basic transaction data For that duration, They could even dictate what format they needed it in. (or Alternatively they could assert they have a system in place already to handle it themselves but I think most would just let the gov handle it in bulk processing than need to make a framework for it)

Then for returning the money, there's a few options. They could either use the existing framework that they have to send returns to cards on file because it's almost certain that they have direct access to every major card network. Or they can filter the master list by the card identifiers at the beginning and send them to the banks/card companies and let them deal with it.

For cash transactions, it would be a pain in the ass, but that's going to be the case for both distributions, because there's no link to an actual identity. What they would have to do is they would have to compare the receipt to the transaction data that they have, which you are right, they could scam you on. However, they would have to know where it was purchased, they would have to know the time stamp, they would have to know the amount spent.

Honestly, the most annoying part of that entire deal would be that people who paid in cash, regardless, are going to have to reach out to some system to say, hey, I spent this money, where's my return? But I don't think fraud is going to be a very big risk case here.

Honestly, they could probably even set up an online portal to do everything for you. You just have to supply the information needed, much like how unpaid claims are