So, 1/3 the production rate per tire compared to a car over 100km. Not to mention half the number of tires. I wonder how much of that is due to the weight difference alone.

It actually appears to be per bike per 100km. I find that quite surprising given it's half the number of tyres, there's substantially less initial volume per tyre than a car's and, as you say, there's a lot less weight on them.

Given their focus on MTBs, I wonder if it's related to the type of terrain being ridden (higher incidence of gravel/sharp rocks than your average road) or different tyre compounds between the two vehicle types.