As often happens here in the The Kingdom of Smiles, I'd misunderstood. Culture dictates driving style. Thais are highly collaborative and mutually aware at a level Westerners don't get.
Think of walking in a big crowd at the State Fair or leaving a baseball game. There are no lanes, no rules of the road, but people rarely bump into each other. Even little kids race around but instinctively avoid collisions most of the time.
Thai Buddhists drive as if they were walking in a crowd. You move in a general direction, stay alert to where others are around you, go with the flow, and get where you're going with no problem. It is very foreign concept for someone who drove mostly in Chicago.
Even in Chicago traffic, you can get in your lane, follow the rules, and dream your way home. Someone might cut you off and you'll curse and gesture at the violation of the rules, but you don't have to keep close track.
Try rules-based driving in Thailand and you'll cause an accident. Thais do awareness-based driving, just as we all do awareness-based walking.
I watched Thai drivers closely. No road rage. No horns. No respect for lanes. There's this expectation that if they pull out in front of you, you'll see them and slow. Exactly like walking in a big crowd, with no rules except to avoid bumping into each other.
Now I drive relaxed but alert, attending to everything and constantly scanning. On a good day I just think of myself as part of a human flow, abandoning expectations about rules, and trusting that others are keeping an eye on me too. It's not perfect. You can still drive Chicago style and probably survive. You might get there ahead of me too. Or maybe not.
Last week I turned wrong way into a one-way alley. A huge black pickup was coming at me. The guys got out smiling, and stopped traffic so I could back up onto the main road. They pointed me to the correct alley, laughing and waving so the old pink guy wouldn't lose face. Next time I'll being paying attention. Thai style.