I can't speak to Walmart's specific rates, but in the past that has been particularly true. In fact, there used to be tranches such that if you were of a certain size, you definitively got a lower rate. The networks—under some pressure from government, I might add—have actually narrowed the gap, but I think that in general, if you were of size, you might still, depending on the magnitude, be able to get slightly better rates. This has been to some degree attenuated over the last number of years.
On May 20th, 2021. See this statement in context.