Again, the issue isn't the contract between FedEx and the owners, it is the subterfuge that Fedex is engaging in to prevent the helpers/employees/slaves of Ground from receiving a decent wage, or being able to collectively bargain. Because they are broken up over a few thousand owners, they can't form a unified bargaining unit against FedEx. FedEx specifically chose this model to prevent the individuals that actually move the packages from being able to create a union.
At the heart of the independent contractor model, is an underlying assumption that the paying party doesn't possess the expertise to either perform the work themselves, or with their employees. It would be a very far stretch to state that FedEx doesn't possess the expertise, experience or resources to hire, train and employ people for the purpose of package delivery.
That is why the IC model of Ground is a sham. It exists to prevent the drivers from being able to unionize. FedEx had no choice but to have Ground and Express as separate operating companies, since if they did operate as a combined unit, there would be ABSOLUTELY no way Express could keep its RLA status. By engaging in this subterfuge, FedEx can keep Express covered by RLA, keep the Ground drivers from unionizing and keep the wages that Ground drivers are paid low, so FedEx can maintain a competitive advantage over UPS or other systems integrators.