I’m not sure what you’re asking. If the U.S. government gives a $500 voucher to an unemployable slob every month and tells them that this voucher can only be used for groceries, doesn’t this add $500 of monthly revenue to the grocery industry’s bottom line that wouldn’t have been there if this person had to buy their own groceries?
The average is about $200 and I think that woman (or someone) would still somehow buy the groceries she needed to eat and that she would buy it at Walmart, and why Walmart instead of Whole Foods in your claim?
I think grocery buying in America is going to pretty much remain the same regardless of the origin of the dollar handed to the checkout lady.