What makes you think that everyone coming into BKK is traveling half-way around the world???? That is not at all a reasonable assumption. BKK serves domestic flights, some costing less than 1,000 THB! 600 THB is a huge additional expense (percentage wise) for such a passenger, many of whom are Thais.

Likewise, there are numerous flights from neighboring countries that are not half-way around the world, many of those people coming from third-world countries and are used to cheap taxi prices.

Regardless though, I know I don't go to Thailand because I want to pay western type prices for things. I go there for one reason - because it's cheap and my vacation dollars go a long ways. Trying to tell people that just because they're flying half-way around the world that they should try to save some money by avoiding an expensive taxi is not reasonable. If I wanted to pay such prices I'd take my vacation at home or some other place. I will gladly take my cheap taxi from BKK this week and will enjoy my inexpensive Thai vacation and will ignore ridiculous comments that suggest that I'm the equivalent to a poor Thai farmer for doing so.