Americans are too literal, irresponsible, and frankly narcissistic to follow something like that. We see a posted speed limit, that's the speed we're going to drive. Or we'll go faster if we think we can handle it (and get away with it). We try to use the literal law to prove our position in court, so "careful and considerate" is too generic of a phrase to uphold legally.

I lived in Germany for a couple years and I was surprised at how responsible drivers were there. Everyone stuck to the slow lane unless they wanted to drive super fast. The autobahns had no posted speed limit, but it was understood that if you got into an accident over 130 KPH, you were 100% responsible and insurance wouldn't cover anything. So people just... drove more responsibly! Americans are too self-centered to behave that way.

I especially liked how Germans would flash their brights if they were going much faster in the fast lane and everyone would just automatically pull over to the slow lane. No fuss, no drama. I do that in America and it just causes road rage. Americans don't like brights being flashed at them. As a matter of fact, in my home state of Minnesota, it's illegal to flash your brights at another car for any reason.