It’s been a while now that they have installed the one-way turnstiles on the departure level at Suvarnabhumi Airport. But, they haven’t been serious about using them. However, that has all changed now as you can see by this recent photo. Taxis can drop people off but these turnstiles are stopping people landing at the airport coming up to the departure level.
While I was there, I saw a few taxis hovering, obviously not knowing that passengers couldn’t reach them any more. I also saw an AOT vehicle with a loudspeaker telling the taxi drivers to move on. But then I saw this taxi driver at one of the turnstiles calling to a foreign tourist. What he did was swing the turnstile half way which left a small gap and then helped the tourist carry his suitcase. The security guard there did nothing to stop them.
So, you can still catch a taxi on departure level if you like but not if you have a lot of luggage. Departure level has the advantage that you get to pick and choose your taxi and driver. However, for new people it is recommended that you use the official taxi rank on the lower level. Here they give you a piece of paper with the taxi license plate written on it if you need to make a complaint later. But, the official taxi queue doesn’t mean you won’t be scammed. The only time I have been cheated at this airport was in the official taxi queue which is why I prefer to go upstairs.