Question about insurance regarding users of the car

Hello forum! This is not a special “1er question” but unfortunately I don’t know where else I could put it. I found that it has a clear effect on the amount of the insurance if you specify another user in the application apart from the owner. (in my case approx. €70.00 / year difference) On the other hand, I have heard that in case of damage, the insurance must pay in any case, so even if a person was at the tax, who according to the contract did not pay for use In this case, the owner only has to pay the difference in contributions. Is that correct? Is it not in every case cheaper to specify only himself (= vehicle owner) as user? How much contribution must be paid in case of damage? (since the beginning of the insurance?, year?, quarter?, month?) Thanks for tips!