It's Thailand, corruption is everywhere - but in a very systematic way. Cash - to avoid traces. The "Card" is a subtle sign to co-officers saying "I'm allowing this, don't get in the way" kind-of-thing. Same as the borders near Cambodia and Laos, borders mear Malaysia are not exempt.

If you get flagged down by a patrol officer, subtle hints will be given and a "fee" will let you off the hook - drive on your merry way away.

If a foreigner's employer cannot pay the "hush money", then it goes viral so that they can earn their promotion but if paid - they keep silent and turn the other way (either way, they get something out of it).