That is the case, which came as a surprise to me.
For things like the road bed, where the force from the surface is going to be spread out more, I'd expect the car to do more damage because total weight would be all that mattered.
But for damage at or near the road surface I'd have expected bikes to do more.
My reasoning was simple: although cars weigh a lot more they are spreading that weight over a larger contact area.
My car for example has four tires each at a pressure of 32 PSI. My bike, before I replaced the tires with wider tires, had two tires each at 110 PSI. Any given small patch of road I drive or ride over would only get about 29% as much force on it from the car as it would from the bike at any given time a tire is on that patch of road.
It would get that force for more time from the car than from the bike if the car is going less than ~3.4 times the speed of the bike and for less time if the car is going faster than that, and more different small patches of road would get force from the car than would get force from the bike.
This is similar to why if I were to put a flat metal plate on my chest and set a bowling ball on top it would not hurt, but if I were to set hold a dagger against my chest and set a bowling ball on top it would likely hurt a lot.
But something is wrong with my reasoning, and it turns out that road damage goes as something like the fourth power of the vehicles axel weight. Whether the tires are narrow high pressure tires or wide low pressure tires, from what I've read, is not relevant.
I'm not sure if that is because I was just wrong about top layer damage, or if it is just that lower level damage is just much more important and expensive, so any difference in top layer damage due to tire size is lost in the noise.