They can't, their tech and industries is still not good enough to do such absorption. Then when they can't, They will come up with excuse of BS reason like respecting IP and they are higher caste and never resort to copy.I hope you guys can keep on thinking this way. There is nothing advanced about howitzers, first try building one yourself and learn. Next import and copy and learn, then improve. Don't jump before you can run, and don't run before you can crawl. Jai Hind!
You can see this pattern repeating in India.
http://news.bbc.co.uk/2/hi/business/3466117.stm
The Indian has been claiming they have license build AL-31FP but until now still can't build a proper working modern turbofan. More or less tell you the so called license production is not exactly what most think. The most sensitive and critical parts still need to be import and tools tech and knowledge are not allowed to pass over to Indians. ToT are not some magic solution.
The fact you see China is able to produce a similar or better product after TOT is mainly thru China own knowledge and industry strength to master completely the product before producing a similar or better one. Not becos Russian really transfer every know how to you.
Same as American, French , British, Israel or even Chinese. The Pakistanis until now still need to import critical parts of aircraft and radar for JF-17 @Water Car Engineer