A sufficiently-motivated lawyer could construct a plausible federal court against Walmart that this 10% discount is payment in illegal ‘company scrip’ (1938 FLSA), and that Walmart owes a 10% wage increase and back pay with penalties to all workers as a result. If they weren’t a conglomerate megastore, one could argue that a 10% discount on non-essential spending is not ‘scrip’, but since Walmart sells in significant part essential goods and are offering corporate discounts rather than lowering prices or raising wages, one would be likely to receive a court date with Walmart over that claim. (I am not your lawyer, these theoretical suppositions are not legal advice.)
I would be very surprised if it's not the case that when you crunch the tax math and look at the % these households spend on groceries and where they spend at a 10% price cut likely benefits all parties much more than a 10% pay bump would.
