Employee unions at the USPS worried about further job losses due to technology. Can't do anything that would decrease revenue, even if it means technological progress.
Of course, that's purely rational. Get a bunch of $100K/year programmers in a room and ask them to build software that improves the workflow of working with offshored $7/hour developers, and see the response you get.
Imagine you're the CEO of a business that is bleeding cash left, right, and center, and someone comes to you with a plan that will reduce your revenue 20% while reducing your costs 50%. You don't think you'd consider that plan even for a second?
I'm not saying such a plan would work for USPS, and definitely not saying Outbox could have brought that sort of value proposition to USPS, but reducing revenue is not always a poor business decision.