What determines the requirement for a guide when a foreigner wants to drive a vehicle he brought from abroad in China?

It is well known that a foreigner who wants to drive a foreign vehicle inside China needs to be accompanied by a guide - which makes this very costly: I have been quoted almost 7000 USD for 2 weeks drive through China, which is not something I am willing to pay, so either I find another way, or abandon the idea for the trip.

One travel agent claims to be able to arrange self-driving in China without a guide, but attempts to get in contact with him are unsuccessful: http://www.laurastraveltales.com/overlanding/overlanding-china-self-drive-and-without-a-guide-its-now-possible/

However lets look at these facts:

1) Foreigners can get a Chinese driving licence in China and drive Chinese-registered vehicles inside China without being accompanied by a guide.

2) For the expensive tourist self-drive through China with a guide, one needs to obtain a Chinese driving licence and affix Chinese licence plates for the vehicle anyway.

If the foreigner has a Chinese driving licence and his vehicle has Chinese licence plates, what makes him still need to be accompanied by a guide, while the same foreigner with his Chinese driving licence could borrow a Chinese vehicle and drive it himself without a guide? What makes the vehicle he brought from abroad, which now has Chinese licence plates, any "less Chinese" then a vehicle he could borrow in China and drive without a guide? What caveat in Chinese law requires one to be accompanied by a guide in one situation, but not the other? What I am missing here?