"why don't we have a subway car industry. who uses more?? why do we need to buy them from canada and japan?"

The state requires that the cars be assembled in NY State. Kawasaki seems to do OK at its Yonkers plant.

But the last few batches of other cars assembled upstate, particularly the Bombardier cars assembled in Plattsburg, have been full of defects and failures, and required extensive re-work. In part because the folks in Plattsburg had never built subway cars, and were given the job just because they were Upstate. Other cars have been assembled in Hornell, where the main shops of the Erie Railroad once stood and there is some railroad tradition.