>For a company like FedEx I don't see the advantage of owning their own data centers. They just don't have the scaling challenges that would require that.

Depends how seriously they're locked onto the postman/route inspection problem. Which is a factor for delivery companies and, depending on how hard you chase it, a driver for almost infinite compute. Once you're playing that game, the economics look very different to most 'not an IT company' IT needs.