I'm not very nationalistic, so I don't care much who wins the Ryder Cup, or who loses. I like watching good golf, especially match play with multiple matches going on at once, so I really like watching the Ryder and Presidents Cups.
That said, it just doesn't ring true that the Americans lose because they don't care, or that the Euros care more, or that the Americans just want to make the team, and so on. That kind of thing in athletics isn't a light switch that you turn off and on; great athletes tend to care all the time, which is a very large part of how they got to the pinnacle of their craft. I'd guess that the 24 players on the two teams, plus many, many others who didn't make the teams, are not very far apart at all in terms of how much they care and how much they want to win. Plus, the concept that a bunch of guys from different countries care more than a bunch of guys from one country just doesn't make sense.
Plus, the Americans don't seem to have any trouble "caring" when the play the Presidents Cup, right? Let's look elsewhere...
So I think that to explain what's happening, it's more about understanding what the Euros ARE doing than what the Americans are NOT doing. And I think that's simple: the Euros have been able to play with an underdog mentality all along, and the BEST way to play any sport, and maybe especially golf, is as a talented underdog.
By whatever measure, Tour wins, majors, the money list, the FedEX standings, whatever, the Americans are the favorites pretty much every time, and that fuels ANY competitor to shove that back, at which the Euros seem to excel. It could be that the "world's against me" ethic was started by Ballesteros and has been successfully maintained ever since, but for whatever the reason, the Euros never seem nervous, only charged up. It's admirable.
I think another factor maybe that the course setups when the Cup is contested in Europe are more beneficial to the Euros than the setups here are to the Americans. That's just an impression, but there seemed to be a lot of holes at this golf course that took driver out of play, and the rough was at least comparable to US Open rough.