My insurance covers my car if I lend it out as long as the driver doesn't live with me. I called the company to make sure I understood the rules about who was covered when my son started driving. Anyone who borrows my car they is covered (if they don't live in my house).
Anyone who lives with me has to get additional coverage to drive my car.
This is just one case. But it may be helpful.
Of course, if you don't get in an accident, you don't need insurance.