In the United States, insurance is regulated by the states under the McCarran-Ferguson Act, with "periodic proposals for federal intervention", and a nonprofit coalition of state insurance agencies called the National Association of Insurance Commissioners works to harmonize the country's different laws and regulations. The National Conference of Insurance Legislators (NCOIL) also works to harmonize the different state laws.
While there are a couple of benefits of collision insurance, the main one is that you can file a claim and receive reimbursement regardless of who was at fault. Collision claims usually get processed faster than property damage claims because the insurance company does not have to spend time investigating who was at-fault. Another benefit is that you only deal with your own insurance company, rather than another insurer with less incentive to pay for your claim. Collision insurance can also be used toward your rental car in most cases, which can spare you from having to buy rental car insurance.