Here in Phnom Penh, for all intents and purposes there are no rules of the road. So there are no sidewalks. Sidewalks are for rich people to park their monster second-hand imported American gas guzzlers. Going up the wrong side in the wrong direction of the road? No problem. Do you want to do a U turn from slow lane on a 4 lane highway -- stopping all traffic to do so is the way to do it. What you find is that it's the 3% of assholes who make a mess for everyone else.

In Thailand people follow the rules a bit more, but they drive recklessly at insane speeds. If you're a teenager, it's not cool to use headlights at night and the first thing you do is remove your mirrors, which no one uses anyway....

But if you go over the border into Laos there are no rules there either, but traffic is completely different from Thailand or Cambodia. People drive slowly, patiently and politely. Lao drivers even put the Japanese to shame and that's a pretty high bar. Laos is a very laid back place. It's too much effort for most people to not do otherwise.

Over the last twenty years I've seen things changing in both mainland China and in Thailand. People are slowly internalizing the rules of the road and following them more with each new generation. You stay in your lane, and your side of the road. You don't run stop signs. You wait for the traffic light to chain to green (or blue in Japan) before you cross a road.

What it comes down to is that rules of the road and road behavior is a collective body of knowledge that takes time to develop in a society. Once that knowledge has been internalized and becomes the cultural norm, then getting rid of traffic signs can work. But there is a learning curve to master that body of knowledge and a correspondingly greater responsibility that goes with it.