The thing is with wallmart, like all other corporations, they can demand 3 months to pay, and smaller companies have to suffer it or not sell to them, that leaves small companies with 3 months of wages to cover, and the expense of the goods provided, before they get the money back, sometimes it runs into 4 months or more, I know as I have been that smaller company, and it is not fun.
Then when one of these big corps goes into receivership, it takes many of us small company owners down with it, due to not being paid from the greedy corps.