Because I don't think that the cultural imperatives that lead to good service are related to tipping at all. Plenty of countries in which tipping is not the norm offer good service as the norm. The prime example is New Zealand. Another example is Iceland, as in its way is Turkey. The reasons for "good service" on a national basis relate to issues such as professionalism, sense of hospitality, empathy, the cultural importance placed on service jobs, and so on. There is no simple answer, and certainly "tip them more" or even "tip with more discimination" is not the simple answer.