IMO this would be a suspect assumption to make w/o data to back it up. You've got two dissimilar materials interacting (in very different modes). E.g. rolling a metal ball bearing on a wood surface would obviously cause the wood to degrade far more than the ball bearing, (and even a wooden ball rolling on a wood surface would wear substantially less due to the mode difference).
(If I had to guess the road has a higher wear as the surface has a tensile stress around the contact patch of the tyre, causing most of the damage, but this is just armchair engineering at this stage).
given the same tires on each vehicle
I don’t endorse the broader statement which would imply the same wear regardless of tire material. That claim is clearly false.
If it were acceleration and deceleration I’d have expected the effect to be less localised, as breaking and accelerating happens over a much longer distance.
But, I have no actual idea. It’s just probably not friction…
I think as a starting point, I would expect that tire wear should remain roughly in proportion to road wear, given the same tires on each vehicle. From this, I would expect car makers to use larger, thicker, heavier tires on heavier vehicles in order to compensate.
Thus I think we shouldn’t accept claims about the replacement lifecycle of tires without knowing these details of their construction. If an electric car is twice the mass of an older ICE car then the fourth power rule would predict a 16-fold increase in road wear. I would then expect the tires on the EV to have 16 times more rubber in order to last the same duration, unless they’re made of some newer compounds which are more durable.
[1] https://en.wikipedia.org/wiki/AASHO_Road_Test