(and everyone else) Two words: Salary caps!
NFL limits how much teams can spend on players so the pie can only be divided so many ways, $12.06M per team in 2012 to be exact. There are NO caps Euro football. Instituting them would be very cumbersome, because while NFL teams play in ONE league, Euro football clubs, if good enough, can play in several leagues at the same time.
Euro football caps would be tough to model as each league has different governing bodies that the same clubs with the same players all compete under. Thus, players are free to move between clubs to the highest bidder, and wealthy clubs can buy better trophy odds. It may seem broken, but that's the system.
And another factor for the discrepancy in salaries between the two sports: far more people worldwide support football than the NFL. I'm just saying...