, my comment was for Noga's initial post. But I was asked for my passport on a city train in Bangkok once and I've had to show my driver's license at a police check stop on my scooter. Everyone should carry a laminated copy of the passport credentials including the Thai visa. Apart from common sense safety reasons, if you ride a scooter without wearing a helmet you're asking to be stopped and fined one or two thousand baht.
Noga, my 6-month visa expired January 9 and I flew out of Suvarnabhumi January 10. I got the triangle stamp in less than a minute without having to pay 500 baht as I had expected. GL.