Sorry, but the answer's usually yes. Most personal auto insurance policies won't cover you if you're getting paid to use your own car to transport people or property for business purposes.
In general, you'll need to buy a business or commercial auto insurance policy if you are a health care worker who occasionally uses your own car to take clients to appointments. The same is true if you use your own car to deliver flowers, newspapers, pizzas, etc.
If you have questions about your coverage -- and policies do differ -- contact your agent or insurance company directly.