Wal-Mart also gets large discounts because of its size. But that doesn’t mean it can open a small grocery store in a town that’s too small to support a normal Wal-Mart. That’s also true of Walgreens, or Best Buy, or lots of other large chains. Big companies have high organizational overhead that makes it hard for them to do small scale projects.

And it’s not a matter of having fat margins. Wal-Mart’s margin is under 3%. Verizon’s wireline operating income margin is usually under 10%, often under 5%.