Although this is not exactly about surcharges, I think you will find it interesting.
As a crew member, I recieve discounts for rentals, hotels, etc..
My wife an I arrived at SLC
for a short visit to oue eldest son, and his family. I went to the Dollar counter and told the sweet young thing that I wanted a car for 2 days. What have you?
She showed me a special, rent a Cadilac for 7 days, but only pay for 5 days rental. Nice, said I but sweetie, I only want if for 2 days, capish?
Well Captain, she said, turn it back after 2 days and you will owe nothing, except the tax, which was 8%.
Hmmm. I told her that Zero times 8% was zero.
She busied herself with the computer, and said "RIGHT! You are SO smart."
I asked her if she would be here in 2 days. Yes indeed, she asured me. I took it, spent 2 days driving it, and when I returned, I fell in her line. No charge.