As well as having proper roads to bike them on, most of America has pretty lame bike infrastructure generally.
Separately, your 22-year-old probably steel-frame bike is probably built a lot better than the average cheap aluminum ones these days, and you've probably taken good enough care of it that it doesn't have a broken or badly bent frame. We're a wasteful people.
edit: your question is akin to asking, "Why are people starving when our farmers are so productive, and the average restaurant/grocery throws out tons of spoiled food annually?". The problem is not purely one of lack of quantity.