What if it's like airlines, where the full-fare and business class passengers subsidize the economy class? Maybe for every 3 cent button, someone is paying more than the marginal cost for their shipping, so it all evens out in the end?
all the major courier services offer same day delivery across the US. I learned this when I flew from NC to CA and left my car keys in NC. I could have gotten them on the next plane to CA for about $300. It wasn't worth it.