A: It does not have enough labor force to meet the service sector and other blue collar work sector demands and growth within it's economy.
Not to much blue collar work anymore with all those manufacturing jobs going overseas.
How about a little supply and demand ? Things would even out after awhile without having to do an end-run around the American people.
It depends on the definition of "blue collar" I guess.
True, imported labor tends to initially be used in the agriculture and service industries, then migrates into better paying sectors of the work force.
What will be the saturation point is anybody's guess.