What purpose does that serve since no claims are made on it?

To whose purse do the funds go?

Are they using a different insurance principle since we get no indemnity no matter how small?

Most third party insurance certificates are fake... That's why people don't bother claim.. if you have a legitimate one, you're legally binded to make a claim when you hit someone or their Property...
Though the reimbursement won't be for you, but for the person or property you hit.. you take care of yourself, except you have comprehensive motor insurance