Iwould suspect it's a mix of old colonial habits of being obsequious toward rich white people and of course, the desire to make some extra money and get tip which is perfectly understandable and not something for which would blame them. People got to make a living and trying to get some tips and good reviews is a perfectly legitimate way to do it. It's just a bit creepy at some point. There is such a thing in my opinion as being "too polite".
I agree, on all counts. A lot of people have a preconceived notion that being white automatically means being from a developed country and/or being rich, which leads to the obsequious treatment compared to people of color (unless they know a person of color is also rich or from a developed country).
Also, I think any privilege from being white--as opposed to just being a native of a powerful country--is mostly experienced by males. As I mentioned earlier, white women in some countries seem to get hassled as a result of their appearance more often than they get any advantage or privilege from it.