This separated fuel economy was introduced in the 1970's. Drivers with trucks and big vehicles got more benefits and their higher gas mileage got less expensive. This was a very good deal for farmers, ranchers or workers, who really needed this cars, but even average people got encouraged by the system to buy a bigger car. They think, it is better to drive a safer and stronger vehicles, that protects you by deadly crushes, but they often forget to drive that SUV as a SUV. This is why safe became dangerous.
However, experts came up with two solutions. Some of them would like to break up with the diversity of size and weight. They want cars to be almost the same size and strength, so that when they crush, the damage shouldn't be so big. Others would like to change the separate fuel economy. Those people who really need the trucks for their job, should still get the benefits, but others, who could also use a normal car in their all day live, should pay extra taxes for the SUV's. This way there would be less monstrous vehicles on the roads and the safety would be also bigger.