How does an accident cost the state anything???????? It does not cost a million dollars to investigate an accident. Unless the idiot driving tries to sue the state for ice on the road put there by mother nature. Then it should be thrown out. The only ones an accident should cost is the insurance companies and the people in the accident. Salt and the damage it causes, costs way more per year in ruined autos than anything else. When a car is rusted beyond safe use in 7 or 8 years that is a problem. I keep mine about 12 years before I get rid of them and they are still in excellent shape. Heck the other day I saw my old 86 Dodge pickup on the road.
Because your highway gets shut down. You pay overtime to clean it up, to have police officers out there, ambulance, etc. You can only bill so much of that back. When good stop moving, they stop going through your state. Here in Colorado, if people from Denver can't get to Summit and Eagle counties to ski, you lose money. If people flying in from out of state, can't get up to the high country to ski, you lose money. If they decide to go somewhere else because our roads suck, you lose money.
Putting Mag chloride down saves time and labor. It prevents snow from sticking and makes it easier to remove once it is on the ground. It also is a great dust control. Salt, sand and mag are all needed. There are times they shouldn't use it, but you need to keep interstates and highways open. You can't just shut everything down in the state when there is a storm here. Buses need to move, people need to drive, goods need to be shipped, etc.
The argument of why do we plow and salt roads is about as valid as, why do we pave roads. Lets just use dirt roads and everyone can slow down.