If you show your asic, they generally waive the charges/commission.
The rates on the other hand are pretty shocking. When doing some contract flying with another airline, I used to change over $20ish at the booth, and then do a swap at a good rate with some of the crew heading in the other direction.
At the time, I didnt have a credit card, and bankcard in the other country didnt work - so I was living off the 10kina hotel vouchers they gave us for free on arrival... Was frustrating checking out and back in every day, but was enough for a coke and kids spag bog for dinner, crew meals did the rest
.