I'm from North of the border and have noticed this, too. Except it is usually the younger ones who are interested, the older ones almost never do. When I started dating my wife I asked her children's grandmother what she thought about me teaching them a native language (Tzotzil Maya as that is what I know the best), and she asked "if that will help them make money". which I think is sad.
Can't really think of much else, I am in quite a bit of pain and my mind is not good at thinking right now.