In much of Asia generally, income disparity is such that middle class-ish people can and do hire staff for a lot of things that they couldn't do to the same degree in the US or Western Europe. Thus things like taxis are cheaper.

And Hong Kong is relatively expensive. My experience in southeast Asia is that, in some places, you can hire a car and driver for the day for maybe $50 or so. So--combined with how horrible driving in the big cities there are--many people just have drivers.