I largely considered the activity of buying low on the internal exchange and selling high on an external one as irrational, as the barrier to entry cost to trade on the internal exchange is minimal, I (perhaps incorrectly) assumed that no one would buy at the higher external price. (Are there even any valid reasons why they would?)
the same reasons that there are 12 prominent exchanges in existance. if you can explain why there should be only one. then you will have your answer.
i would explain the answer but there are too many reasons to list them all.
summerised
features(troll boxes, put and call options. shorts vs plain standard no fancy feature, basic trading)
barriers of entry (kYC or no kyc preference)
liquidity(how much volume(your buzz word buffer))
trust that its not going to fail
trust that the prices move enough to make profit on
limits or lack of financial limits to deposit/withdraw (AML or internal profit making vs zero fee trading)
arbitrage oppertunities..
i left that to last. because although your mindset might be a stable currency for consumer spending of goods and services.. exchange day traders love the opposite. they love price movements.