Just to be picky, I have to point out that there are 4th and 13th floors, they just call them something different. (A few buildings use the 13th as a maintenance level.)
Something similar is done to make buildings seem taller. Usually the reported number of floors on a building is equal to the highest floor number. If they skip the 13th, it's off by one. And some buildings skip 10 or 20 floors.