I don't know. They've applied for and received Top Tier approval, which means they've pledged that there will be their chosen additive in a concentration at least that which they provided for testing. Top Tier makes no requirement of where the additive is inserted in the process.
But they do tell you the trade name, who makes it, when it's pumped in, and how it's been tested. At least they have in publicly available documents. They no longer say it, but I remember an older document that noted that the then "Clean Power" detergent additive was UltraZol 9888 from Lubrizol, which may have been a custom additive made for them. It's kind of odd because there is no UltraZol 9888 on the EPA website, but there is a "Lubrizol 9888". Not sure about the discrepancy.
The document from that 2013 presentation shows how they do it. They've got a keypad to enter the volume of fuel delivered and it's supposed to meter the detergent additive. I've looked around at some stations and they definitely have the lavender colored hatch in every station. Some even have above ground tanks for the detergent, and that's been verified. About 8 years ago I found a permit application Costco had in North Carolina where they described their setup including additive-only tanks and a metering system for that additive, specifying a 1:2700 ratio of additive to gasoline.
We talked about it years ago, although a lot of the links are dead. I'm not sure what you think they need to do to prove that they're actually doing what they say they're doing. Certainly if they're not providing additive in the 5x EPA LAC that they claim, it could be fraud. Or they could be in violation of their Top Tier licensing agreement.