Why Don't Athletes Sing the National Anthem?

I love the Olympics. Summer, winter, either one, I love watching them. I enjoy the watching the sheer joy and determination and "the agony of defeat," but there is one thing that has been bothering me lately. When Lindsey Vonn was standing on the podium after receiving her gold medal, the American flag(s) were raised and the national anthem began, but she didn't sing or mouth the words to our anthem. I noticed that other medal ceremonies as well and it just is a little bit disheartening. I know the song is awful to sing because the range is so wide. Those high notes are killers and I usually drop down an octave or just mouth the words at that point in the song, but out of love for my country, I sing it. It would be nice to see our American athletes at least try to sing while their country is being honored. I noticed that the Canadian snowboard gold medalist seemed to belt out "Oh, Canada" when she was on the podium. It has occurred to me that perhaps American children are no longer taught the words to our national anthem in school; it would probably offend someone. Maybe that is why these young athletes do not sing or at least pretend to sing the song. It is a sad thing though, and I am going to make sure my kids know the words even though they will probably never have to stand on top of a podium in front of the whole world and sing them. ****At least Lindsey Vonn did have her hand over her heart--that is a start, I guess.......