Well, actually. Holman outpost buys niobium ore. You dont have to haul it to rheinland. Gold ore is sold in Kenningston shipping outpost I believe, and in Detroit munitions. Wanna guess does anyone sell there?
There are points where you can unload your ore for a less price. Usually far less price, but they are there and they aren't so commonly used.
However, I don't see a point in making gold ore sell in Rheinland, Kusari and Liberty for same price. People will never sell to a certain place then but always use the closest one. Liberty. It's like 5 jumps away.
Keep in mind that not all the houses have same commodities.
Liberty, Rheinland, Bretonia etc love optronics. Kusari loves gold, hi-temp alloy, mox, etc...
There really is plenty of stuff to trade around.
Ok so maybe while gold - military vehicles makes 75mil in 2 hours, while Vip / Passangers / lux consumer goods makes 68, but is it really such a dire loss?