For their needs. Their JOB may be in the construction industry and they need all their tools to do the work. Table saw, plywood, doors, windows,toilets,tubs, drywall sheets,bricks, bags of concrete, lawn turf, the dining room table, the sofa, the 96" screen TV, etc,etc,etc. Farmers carry bales of hay on their trucks, many bales, or pull trailers of horses, boats, long ladders, planks, scaffolds.
. They can't do this with a SMART car.
The drivers do not like to pollute the air any more than you do but THIS IS ALL THE AUTO MANUFACTURER'S MAKE. This truck with this engine. It is not like the driver has much choice. It is up to the car R&D department to come up with something just as useful as we have now, but does not burn as much fuel. Not burning the excess fuel pollutes less.
These SUV truck drivers are not going to resort to the horse and wagon model because they have so much work to do and horse can not get there fast enough.
. Pollution is more a problem from the cars because do you need a car to go to the corner store? It is close enough to "walk"? That is why it is on the corner. I hear your answer already, I am too fat to walk that far. Well, you would not be so out of shape if you were walking more.
. so often I get asked "what did you do today"? "DROVE AROUND AIMLESSLY BURNING GAS" is the reply from many people. In general, we are the problem. Bad Habits.