It's been a while but I think that only applies to independent freighters where the operator borrowed the full cost of the ship (and thus has very high bank repayments each month).
If a megacorps put down 1/2 the price of a ship as a downpayment then they would have much lower monthly repayments.
A really big megacorp might even have their own shipyard.
(This is one possible explanation for a system with an A star port and a population in the thousands - private shipyard).
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Say a megacorp has a contract to supply 100 gravs a month to another system J3 away with a J1 route available and say each grav needs 10 dtons including packaging that's 1 x 1000 dtons a month via the J3 route or 3 x 1000 dtons via the J1 route
so 1 mill vs 3 mill CR.
The J3 option is clearly cheaper for the megacorps but if J3 isn't economically viable for an independent freighter even if fully loaded then it still won't happen unless the megacorp uses its own ship.
So the question isn't always just independent freighter vs independent freighter; in some cases the options might be freighter vs megacorp's own ships.
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So the key point is bank payments. It's only uneconomic cos of the bank repayments and those are based on some random dude - like a player - wanting to borrow the full price of a ship from a bank at the repayments in the rules
but if someone - like a megacorps or a very rich free trader player - with enough money to put down a large downpayment then they will have lower monthly repayments
(although it's been a while since I did the sums for this so may have missed something.)
What you want to do then is ROI, and also how much the investor wants to reinvest into new ships and how much money they want to bank from profits.