As one of my friends, an SAP consultant, said - "The value of SAP isn't that it's actually good, but it's predictably scalable"
As in - you can setup a process in Germany, then replicate it globally with predictable accuracy. And predictability matters a lot in stable low margin businesses. Walmart can't spend a few billion on a project that may have -100% to 400% return value, when. they have the option of having a reliable 20%-30% return value.