Why does Boeing have a contract for their starliner? Did you see how they tried to stop SpaceX with their government influence?
Stupid analogies aside, if the southern colonies had established a ship-building industry or had run their own shipping lines then there is no reason why they would not have been in a position to compete with northern colonies and, after independence, gotten their own share of mail contracts. Yet there were no colonial shipbuilders or colonial shipping lines in the south. I suppose the northern colonies conspired with the King to undermine all the attempts to establish them? Or some similar conspiracy theory from your fertile imagination?