Because it's easier to 'steal'? Their laws are different so they don't see it as stealing and have no problem with it. Each country is unique and I'm happy US can't force their IP laws to everyone around the world.

You know that exactly the same argument was made against the US, Germany, and Japan at different points in time, right?

It's coined "piggyback economy" where the first move innovator ends up absorbing all the risks in developing the product and getting it to the market. The second mover then simply improves on the original product likely with ton of issues as they have to distribute their resources throughout the full journey the product makes it from the drawing board to the consumer. The market is there and the second mover is able to "catch up" when the product is as good if not better in quality which finally leads to the exit of the first innovator signaling new entrants that will put pressures on the second innovators margins.

Lots of original research in the US is done by Chinese PhDs. Have you not done your research? So is it really stealing? Or the US is taking advantage of the best and brightest from China?

Because its not efficient, why reinventing the wheel ?

Problem is that they've already caught up. Now they are competing and passing in some areas.