The only time the state asks for proof of insurance is at the point where you go to register the car. When you buy a car from an honest dealer, they apply for paper plates at the moment of purchase, which requires you to have insurance.

However, you can buy a car from a private party, sign the title over, and just not apply for plates, temporary or permanent, from the MVA. You would do this if you didn't live in Maryland and were going to title the car in a different state, as the MVA won't give temporary plates to people who don't live in Maryland.

So let's say you (a Maryland resident) buy a car from a private party. You can get a Maryland title without needing insurance. But, you can't get plates from the MVA until you prove to the MVA that you have insurance. You don't want to pay for insurance. What do you do instead? You buy fake temporary tags from a guy off Craigslist and drive around uninsured.