In Argentina, where I am currently based, the custom is to tip restaurant waiters 10%, while cab drivers get no tip at all. Obviously, this is very different from American norms.Tipping customs in other countries diverge from both Argentina and the US.

What explains the variation? Is it just a result of chance? Are there deep cultural differences at work? If the latter, how does one explain differences between countries with similar cultures? Perhaps there is a good academic paper on this subject that I have missed. If so, comments are open.