@Mike *******
You are totally confusing a "visa on arrival" with a "visa exempt entry" :(
People from 21 countries BUY a 15 day visa on arrival for 2000baht when they enter the country,
people from 50+ countries get a visa exempt entry for free when they stamp in and people from 44 of those can only get two 30 day visa exempt entries by land in a calendar year :) .