when people have no option but buying the insurance, the insurance companies can easily raise the insurance price, becuase if you don't buy, you will be fined by the government. They can also fix price without any evidence.
When people lose the choice, there is no check on the insurance companies'a behavior. I don't believe the government can be trusted to do justice all the time. Corruption and high cost in lawsuit can drive the system to none bearable in time.