system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do busy city roads take longer to degrade than lesser used county roads?
gpt
Former paving contractor here. Busy city roads are usually built to a  higher standard and get more maintenance than low-use country roads. 

To the causal observer, roads all tend to look the same. But underneath the black asphalt you see, busy roads are built stronger. More gravel base, and often a layer of concrete provide a strong long lasting structure that can support lots of traffic. 

But this strength is expensive. Municipalities often cannot justify the extra expense of building this strength on country roads that do not get used much. So they sometimes degrade more rapidly.