Hong Kong is a Special Administrative Region of the Peoples Republic of China.
There is no argument about that, unless you just purposely ignore that info.
You do realise that the 99 year lease between the united Kingdom and China, of Hong Kong's foreign occupation, is no longer valid ?
Yes you acknowledge, or no you don't ?
And for the record, having driven in mainland China, in Shen Zhen on many occasions, and from Beijing to Wu Tai Shen, via Shanxi, a 7 hour drive in our company's brand new VW Santana, I think I am experienced enough to comment.
The mainlanders that I have seen drive in my area of Hong Kong, which is located on one of two, of the busiest arterial routes via 2 border crossings, seem to stick within their lane, well behaved in my opinion, minus the lane hopping/splitting that is done across the border. Their driving behaviour is definitely adjusted here, or they cop fines from the HK rozzers, and as most of them are just company paid drivers on $700rmb a month, copping a $320HKD fine isn't appealing, unless their boss in the back seat, pays....
The HK police are the only difference, and if they were ever given control of the roads in the SZSEZ, driving culture will improve, evntually equalising.
Make it a $1500 fine on the spot for lane splitting, and they'll pull their heads in across the border.
The reality is, long term within 2 decades, HKSAR and SZSEZ will combine as one....