Guvnor,
Why don't we take an index of how many days weeks, or months pay, are needed to buy consumer durables in the relative countries.
Items like cars, refrigerators, stoves, TV Stereo, etc.
You could include rent and food too, using the same yardstick.
In other words we are using relative dollars not absolute dollars.
But hang on, if fares are in absolute dollars and costs are in relative dollars, who pockets the considerable difference? Surely no consultants here, Guv??