I designed highways. This is correct, and this is why weight restrictions exist. Noncompliance is not that much of an issue, and there are occasional permitted loads anyway when there’s a need to haul industrial equipment or unusually large objects.

The most important thing to remember about flexible, pavement lifespan is that asphaltic pavements are not designed to last forever. The asphalt binder will eventually oxidize and become brittle even with no traffic. These surfaces are meant to be consumable bearing services that last for 10 or 20 years and then have to be removed and or overlaid.

I’ve done a lot of trips on I5 from Central Valley to San Diego and those stations were open most of the time and I usually did it near holidays in November/December/January. Enforcement probably depends highly on location and amount of traffic.

The damage scales with weight. Cars cause less damage because they are lighter. Heavier cars still cause greater impact.