I think a big factor is health insurance in the USA. If you are in your 40's you probably have a partner and kids. Your company will have to cover all of this,

I think a big factor is health insurance in the USA. If you are in your 40's you probably have a partner and kids. Your company will have to cover all of this, and if the kids get a condition things can be expensive. So, I think that they consciously focus on younger people to drive the costs down.