Bangkok Suvarnabhumi Airport (BKK) has some of the worst immigration lines in the world. I have had times that took up to 2 hours to enter the country. Typically airlines provide an immigration Fast Track Card that allows a much speedier immigration processing in a premium lane. These Fast Track Cards are provided to First and Business Class passengers, as well as to passengers holding elite status as a courtesy from certain airlines.
Bangkok is just one of numerous airports in the world that offers premium immigration and customs service for passengers. Similar service can be found in other large airports such as the premium arrival service provided for British Airways Premium passengers in London Heathrow.
However, from 1st July onward, Bangkok Suvarnabhumi Airport (BKK) will be retiring the use of these Fast Track Cards and allow only First and Business Class passengers to use the Fast Track facility.
This is because a scandal was exposed recently that certain individuals are illegally reprinting these Fast Track passes and reselling them online for a huge profit. It is reported that typically these Fast Track Cards are issued for 18-35 Thai Baht a piece to airlines and agents, but certain rogue individuals have been selling these cards to tour groups and other individuals for sometimes over 1000 Thai Baht a piece, reaping huge illegal profits.
The biggest loser in this scandal is, of course, Economy Class passengers holding airline status. They will no longer have access to fast track immigration as a courtesy from their airlines.
However, there are other ways that passengers flying Economy can use fast track immigration facilities. Airports of Thailand (AOT), the company that runs Bangkok Suvarnabhumi Airport (BKK) offers limousine services that include fast track immigration. Or a premium arrival-pick-up service offered by BFS, a company owned by Bangkok Airways. These are just one of the numerous ways that you can still get premium service for a price.
(Some of the info used in this piece came from external sources indicated in the hyperlinks in the article)