Only slightly related to your post, but 3 months ago I did a border bounce by air to Singapore. I received no stamps there, arriving or departing.
At Bangkok Don Mueang airport the IO called me around to her side of the 'booth' to review pictures on her screen, which were very poor images of me. She had to ask me if that was indeed 'moi'. I confirmed, but only later realized they were taken in Singapore... I think.