While it is true that goods and sevices are cheaper in Thailand than in the West, I am not sure that this is reason to apply upon the Thais a different set of moral standards from our own. Short changing customers is obviously dishonest. However, getting change back in small denominations is very common in the USA. In trendy venues in New York 20% tip is expected. While many customers pay by credit card, cash payment often yields change in bills or coin smaller than necessary, as a matter of convenience to the customer to pay the EXPECTED 20% tip (even though the service may not warrant it). I am sure when the US re-issues the new dollar coin (to replace the failed Susan B. Anothony), we will get a lot of change back in dollar coins. If the change is the correct amount, I am not sure that this is something to get so upset about, since it's done in our own countries and no one bats an eye.