Well it might be off, as there are other factors, but I wasn't meaning it as hyperbole - road damage is proportional to the fourth power of axle weight, and a typical bus weighs about 10 times the weight of a compact, so damage would be roughly 10^4 times larger. This is called the "Generalised Fourth Power Law" and there are tons of links about it:

https://camdencyclists.org.uk/2020/06/the-fourth-power-rule-cyclelicious/

(Which btw, you can apply the other way and state that you need an insane amount of bicycles to match the road damage of a single car).

If they took the top end bracket of SUV weights and the bottom end of bus weights, they could have reached vastly different numbers. I used 1800 kg (large sedan or compact SUV) and 18000 kg for a bus (the mercedes Benz citaro starts at roughly 18500 kg), to keep the numbers simple.