How good are American roads?

> Interestingly, in all cases urban roads are worse quality than rural roads, presumably because they see higher traffic than rural roads.

There's more infrastructure under urban roads. Crews come in to fix some utility, shred a section of a lane, patch it poorly with dissimilar materials, and leave.

You're probably also going to have far fewer massive vehicles on those rural roads. More things like pickups yes, but probably considerably fewer semi-teicks and busses and fire trucks and cement mixers what not. Those big trucks passing through are going to stick to interstates far more often when going through rural areas.

We have large farm machinery though.

Large machinery, but typically very low ground pressure. After all, that same machinery is designed to operate on arable soil without sinking or bogging down. It is my understanding that it is ground pressure more than absolute weight that correlates to road surface damage/erosion.