I know a few cases of people who made an insurance though an insurance intermediary and they were deceived. The intermediary received the money, printed the green card (that's how we call the insurance document here in Portugal), but never actually made the payment to the insurance company... So nothing like confirming with your insurance company if you are in fact insured!
I am not sure if you have an Insurance Commission or something similar in Portugal but these intermediaries should be reported to them. It is things like this that cause all of our insurance to be much more costly than it should be. An Insurance Commission is basically a group that makes sure the rules are followed and agents are properly trained and certified to sell insurance. You do make a good point, it never hurts to "double check" with your actual insurance carrier!
Accident insurance fraud is becoming a big problem for the insurance companies in England. Organised crime orchestrates car accidents to win compensation. The insurance companies are losing significant amounts of money to this fraud and while their profits do not bother me, it means the rest of us have to pay more for our insurance.
That is a big problem in the USA as well with all types of insurance. People wonder why our premiums keep going up because they don't realize the things the dishonest people do to make a buck.
Plenty of people pay the first premium and then nothing more to just get the card that says they are insured for a year. As long as they don't get pulled over, they are fine. Until they hit you and you're not.
I don't know if they reported them or not, I am sure I would. If I have an accident and I am not insured I wonder who would pay if it is my fault... A huge mess I imagine.
Insurance fraud abounds all over the world, obviously in different forms. Unfortunately, liek shoplifting, there really isn't a way to stop it in it's entirety without preventing people with legitimate claims from accessing their benefits. We all end up paying for it through higher premiums, lower payouts for claims, and harder to get insurance premiums. Sad but true.