This is not exactly the fault of VW/Renault etc. China has quite explicitly encouraged technology transfer as an important strategic imperative for their local firms, so if these companies wanted to play in the (obviously growing) Chinese market, technology transfer was the price to be paid.

(Another example of this is the high-speed trains in China - the first generation was built by JVs with Siemens/Hitachi/etc with an explicit policy of technology transfer, but the newest trains in China are now local, built on top of the technology that has been acquired.)