condo wind mit roof

Someone with a downstairs unit in a condo about 35 years old with no opening protection or rated windows or doors had a wind mit done and got a 25% discount on their insurance based on the roof. Is this because it is a reinforced concrete roof with a waterproof membrane? Does this type of roof always merit that deduction?
Any info appreciated.

Yes and yes, flat concrete structural roofs are an automatic 80% I believe.

True, reinforced concrete roof systems have their own built-in discounts that override just about everything else except maybe opening protection credits.