They have never forgiven American IT workers for demanding - and getting - market rates during the dot-com boom. They work very hard to make sure that can never happen again.
But even beyond that, IT as a discipline is not valued by American industry. It isn't seen as a key part of the business, but as something many prefer to outsource, when they can.
A very short-sighted and dangerous way to look at things in this day and age. However, I've seen it myself over and over.