yup but things are changing very fast in China re the tipping culture. And where it is not, it is also a bit two-leveled at times- for instance its illegal to tip taxi drivers but in places like Beijing, where taxis are difficult to just step onto a curb and hail one, the drivers will ask you to give a fixed rate much more than the meter taxi. All the tour guides and big hotels, its very usual to tip. The guides there have the same kind of understanding with tourist shops on commissions.
And with due respect, there is absolutely no comparison to the service level in Africa and China. I have been to only 20-25 odd countries in the world, but I have never seen this standard of service outside the countries in Africa- even the cook who uses all kinds of basic stuff to put together a splendid meal in a mobile safari. Another thing I have seen in Africa- if something fell really short of your expectations and you give the feedback there and then, most often the crew tries to juggle up something really wonderful to compensate. Try giving feedback in China, HK and even in some European countries, and its not taken well at all.
There is no reason from a cultural point of view and no reason at all except that cost of living in Africa is much lower than in the US, that warrants a bigger tip in the US. It just seems counter-intuitive to me given also the huge disparity in service and standard of life.
I know the link at the start is a quite unacceptable to say USD 100 a night in expensive lodges and at the very least they should have added what you are comfortable paying but just for argument's sake, how is it really different than saying 15-20% tip in the US? 8 years back when I was in NY the first time, 10% wasnt so bad, but in 8 years it cannot be a culture thing if the target is now 15-20%.