@Ter***
, a visa on arrival and a visa waiver or visa exempt are completely different things.
People from 21 countries BUY a visa on arrival when they enter thailand for 2000baht and it lets them in for 15 days.
People from 51 countries get a 30 day visa exempt or visa waiver entry for free.
People from 44 countries are limited to TWO 30 day visa exempt entries in a calendar year.