I believe you will find alot of that is fuel surcharge...
Some airlines charge others don't...
e.g. I am in the VS Upper class lounge now (thanks to my BMI gold card) on a reward ticket from CO, 50k miles and only about GBP 72.58 and GBP18.27 service fee.... Was looking at lufthansa F (miles only) but the tax was about GBP 378....
Got to pick which carriers you fly on to avoid these...
tht