Interesting you mentioned cab drivers -- when we first bought our timeshare in 1997, we did our homework. Both Fodor's and Frommer's clearly stated that it is not customary to tip taxi drivers, as unlike in the U.S., they are well-compensated. They also trumpeted the government-set taxi rates. Well, by now there have been so many U.S. tourists throwing tips at them that some of the drivers now seem to expect tips from Americans, even though they will never see them from local users. Adding insult to injury, some drivers have become so greedy they now ignore the government-set rates and charge whatever they want (A $17 taxi from the airport became a $40 one two years ago when an unscrupulous driver demanded $20 from each of us sharing the cab). This os one more reason why we now rent a car and drive wherever, whenever we want.