“Because every bit of technology they have was either given away, sold on the cheap, or otherwise flat-out stolen.”
I cannot prove this, but I was told by a professor at a university in the PRC that they obtained the plans for their rockets by going to the Moscow Archives and using a photo copier.
They literally photocopied the designs of a Russian rocket.
That is strange enough to have been true.
So much of this is floating around in the public domain anymore, I can fully believe that they could sweep up the nuts and bolts of it out of a Russian archive and engineer it to their needs and liking. It’s amazing that more of this type of thing hasn’t manifested itself. It probably has, but is out of the public eye.