This just doesn't sound right. Unfortunately, insurance companies are allowed to cancel policies for any number of reasons including accidents. Unfortunately, it's true. You could always cancel Allstate and switch to State Farm or Geico or some other company but you would have the same experience. The answer lies with your state legislature.
Insurance is regulated at the state level.
If you don't like the way insurance companies operate in your state, the answer is to organize others who feel the same way and start putting pressure on your state senators and representatives. I told them that this fee was extremely high considering what I had to pay for my daughter. The secretary advised me that if I could find a cheaper rate, be her guest. Allstate sent my bill to a collection agency. I called my agent, the secretary picked up and she said I owe the money and that it was a state law.