5000 Transport Flying Dublin --> New Berlin with gold ore ~10.000 s.c. / Unit = 50.000.000 s.c.
So if he makes 50 million he can pay the Miner 10 million and he is still left with 40.000.000 s.c.
now assuming he is from Bretonia he still will fly to New Berlin but this time he will get 4.473 s.c. / unit = 22.365.000 s.c.
1/5th to the miner would mean the miner gets 4.5 million and the trader is left with 17.892.000 there are trade routes with non contraband that are more profitable...
If we take pirates into account the hole change makes even less sense:
Without the change a pirate could easily demand 10 million credits without having much of a problem. If he did then the trader would still make around 30 million meaning it was profitable to make the run.
Now you encourage Cargo piracy. Lets assume that its not a 2 man pirate operation and assume he is flying a BWT, that means that he can when properly equipped carry around 3200 Units maybe less.
First ironically the pirate makes more then the trader if he pirates him on the way to New Berlin because hecan sell the ore for 4726 s.c. / Unit (I guess whoever came up with those numbers likes to fly pirates?) that would mean in a 3200 Cargospace scenario he would make 15.123.200 s.c. which is more then the 10million but he has to move it and cant pirate again so its only a bit better then before.
Whoever the Trader now can only sell 1800 Units of cargo. Which means he only gets 8.051.400 credits assuming he payed the Miner 4,5million he just made 3.5 million for traveling from dublin to New Berlin. Who will do that ? And that is assuming that he has a real 5000 Transport this gets even more critical if he has a smaller transport.