I kind of wonder if Home Depot just issued a blanket statement because they didn't really know how the system works. If a guy who works for the government shows up with an IMPAC credit card to buy some stuff for the local military base, you just scan the card, have the guy sign the reciept, and he's on his way with the stuff. As for cash purchases, I don't think the govt. even does that anymore. They make everybody use direct deposit and material is only purchased with purchase orders or credit cards because they have minimized cutting checks and disbursing cash, at least as much as possible.
The real paperwork and audit hassle comes when you want to be a GSA-approved contractor so that you can sell them large volumes and/or high-dollar stuff. I'm guessing that the big boys at Home Depot didn't know this and just issued a blanket policy, or maybe the govt. did something to really piss them off. Who knows?
A sufficiently creative government attorney could argue that by taking Federal dollars, in any form whatsoever, the Home Depot company opens itself to onerous Federal regulation. True, the GSA audits and paperwork and other Federal regulations are intended for the large volume supplier, but, the Federal government will exercise regulatory control over any company it can, just because it can.
I can definitely believe that! /no sarcasm