The whole point is that the IRS rules make no fucking sense.

Here is another that is completely contradictory and makes no sense: The IRS does not accept ATM receipts as proof of anything. Not proof of balance in accounts, nor proof of money withdrawn for a purchase of anything. To the IRS an ATM receipt is a small piece of trash.

But when you make a log of your casino play to satisfy IRS requirements, if you made an ATM withdrawal, it is recommended you attach that to your records. This piece of paper that they don't recognize as proof of anything, somehow validates, or "supports" your written records. Even a receipt from the casino for lunch or dinner, somehow supports your written casino records. It could be a receipt you pick off the ground that wasn't even yours. Makes absolutely no sense.