Insurance premiums are determined on the basis of actuarial studies. If a certain insurance-covered practice statistically proves to be more dangerous than another, the dangerous practice leads to higher premiums. If passengers in large vehicles are hurt at a lower rate, it only makes sense that they pay lower premiums for their medical insurance. On the other hand, if large, safe, tank-like vehicles are crushing other cars and people as if they were cardboard, the actuarial tables will show it, and the premiums will go up. You can take that to the bank.
Insurance companies are in business to make a profit.
Before they adopt a pricing policy that consciously lets big-vehicle owners or anyone else tap into their benefits without paying the proportionate cost, Ford Explorers will float on the air like seagulls and Grand Cherokees will do cartwheels in the village square.