I think it's because, in the end, with cars you can pass the costs directly to consumers. With industrial and commercial engines you tax business. In our day th

I think it's because, in the end, with cars you can pass the costs directly to consumers. With industrial and commercial engines you tax business. In our day they have greater political power than voting populace. Same deal with California and water. Easier to force residents to conserve, the businesses using 90% of the water are polically protected