I interviewed for a position at FedEx's main office few years back, and I was asked "Why should FedEx avoid a shipping-rate pricing war with UPS?" Their answer:

I interviewed for a position at FedEx's main office few years back, and I was asked "Why should FedEx avoid a shipping-rate pricing war with UPS?" Their answer: we don't want to shrink the value of the overnight shipping market. That sounded reasonable at the time, albeit collusion-y, until I learned about market elasticity. Now it just sounds lazy and protectionist.