There are a lot of other personal uses for vans and pickups and other heavier duty vehicles in rural areas which require more power to haul things beyond farmers. Moving large amounts of wood and cleared brush, having off road capabilities that include lots of torque, and other stuff that has nothing to do with highway driving are common outside of cities.

The exemptions should be handled in a way that discourages owning such a vehicle for personal use in an urban setting without being tied to a business. Hell, that could involve who the vehicles are being advertised/targeted to for in addition to literal vehicle types.

The problem was not changing up when it became apparent that the outcome was discouraging high mileage small cars for commuting. Overthinking the how to discourage laerger trucks misses the point that car companies leaned into large vehicles and advertise to convince the population that they needed larger vehicles. They could have been barred from advertising large vehicles.