In Ontario, the Compulsory Automobile Insurance Act [1] requires that all owners/lessees of vehicles take out insurance policies. The Insurance Act [2] sets out that the minimum amount should be $200,000.
$200,000 is a much better floor than, for example, Ohio's $25,000. An Ohioan friend was injured by a motorist who had the minimum coverage. Her care cost more than that. The motorist who caused the injuries didn't have a lot of assets and she was unable to recover the excess from the motorist.
Still, there are some perhaps unintended downsides. Canadian rental car companies, as the owners of the vehicles, are obliged to provide $200,000 insurance as part of every contract. As a result, it seems there's not much market for them to sell excess liability insurance, and none do that I'm aware of. I, as someone who has plenty of assets to lose if I injured someone, would happily buy a higher liability insurance. Doubly so when I rent a car to travel to the US, since the terms of the contract are often "the rental car company will provide the minimum insurance required in the jurisdiction where the claim is incurred".
I agree that 200k is a much better minimum. Although I would think a deposit of $200k should be just as good as a policy of $200k... But the Ontario law doesn't allow for a deposit.
I wonder if there's a speciality business available in Ontario for single customer insurance, so individuals or businesses can self-insure without risk pooling.