Doug (unusually) is correct here. Look at the all those who forego representing their country (normally it's free as well) to do other less important races, only because they get a nominal appearance fee or prize money of a few thousand.
Mind you, where are all these NXN and Footlolcker kids when the world Junior XC trials roll around in February? Running some irrelevant indoor HS meets as opposed to trying out for the world team!! So many people simply haven't a clue. Yet the US gets destroyed on the world scene (especially the men) at XC these days! Geez I wonder why!! This also transfers over to the Marathon, which is also why so few American men can even break 2h10 (a time that was elite 30+ years ago).