To get 65,000 for a pre-season football game in the US you could have a half-time with show with both Shikira and J-Lo pole dancing in the nude and I still don't think you would fill the stadium if the game didn't mean anything.
Well and the only reason why you get 65,000 to watch Chile vs Peru is because of immigrants would will drive from far to get to watch a rare appearance by their home country team.
Friendlies are a way to get revenue and promote soccer. The US has become a big destination for friendlies because the high ticket prices they charge. If Real Madrid, Man U, Barca, etc etc come to the US, they can fill a stadium with high price tickets, many over $100 to watch a game that means nothing.