Originally Posted by
grouse
For the sake of argument, I can make up numbers too!

That proves nothing.
If you want to support your argument, look at the breakdown and see how much is due to actual taxes like air passenger duty, and how much is due to "fees" which are actually set by the airline, and may or may not bear any relationship to their costs at the airport. Ryanair, in particular, has been scrutinized for posting airport-specific "fees" that bear zero relation to what they are charged by the airport operator.
So then what supports the outrageous taxes at LHR? It seems that all airlines coming from the US add up $250 for RT via Heathrow?