You might be right, but the thing is, other countries can do things by fiat.

But the US democracy/political process plus the different states can lead to "vote for this speed limit" as well as widely varying traffic laws in different states.

Personally I think if you want super low speed limits, instead of just enacting them and expecting compliance, maybe use traffic calming devices and other reality-based methods. The united states is not one culture.

I found japan interesting. japan is a high trust, high compliance culture. A (US) friend lives there most of the time with his japanese wife and he told me how things work. The driving tests are very comprehensive and expensive. Also, if you're from the united states, they fail your test the first time you take it. They just assume someone driving on the right should not pass. They don't seem to do that to folks from australia/england.