Short Hauls are getting cheaper, long Haul is getting more expensive because the cost of Fuel. Used to be the cost of flying from Europe to Asia was the same as say flying from London to Greece. Now with the Low Cost Carrier book online revolution, a person can fly from London to Greece and go on vacation cheaper.
European people are staying in Europe more for Vacations, and exploring Europe. Most European young backpacker know the world outside of Europe better than Europe because the cost to Backpack Europe is atrocious compared to South America or Asia.
American know or pay to Backpack Europe more, but that is just because this is status symbol compared to saying they did Asia or South America. Backpacking is about saying to friends, I went here, more than actually saying I went here because I wanted to see this. Bragging helps promote some of the worst places on the planet for value of trip, compared to what you see.
Europe is not cheap with trains, it is cheap by internet purchase of LCC. Asia is not getting cheaper by Low Cost Carriers, inside the USA is slowly getting cheaper, but no public transport after you arrive.
Africa is just nuts on price, central America is best by bus, Mexico is Mexico. Arab countries are best eaten one at a time, then fly the coop, best to get a 10 day layover as you fly from Europe to Asia, included in the fare, easy to do in Bangkok with Jeroen,, give me a ticket please with 20 days in Manila on the way to the USA, or give me a 10 days in Dubai on the way to London.
The cost of fuel has made the long haul more expensive, plus the dollar exchange is not good.