We don't know Walmart's feelings, they may like the arrangement. Business go cash free for all kinds of reasons. Customers that use credit spend more money than cash customers. Walmart probably isn't one of those places that benefit as much as a pub but they may have a small credit spending boost that covers the fees.
Walmart is a really smart and data driven company and I'm sure they've weighed their options about what is effective business practices for them.
A walmart branded card gives them money back though, I see it more as a way to slow the bleeding on transaction fees they are going to have to pay no matter what. See my cousin comment on the whole "CurrentC"[0] debacle for where I am coming from on this. Walmart has a long history of sueing the credit card companies over their rates and had tried to make a competitor.
