Blind spot

Ohio Revised Code
4513.24
(B) No person shall drive any motor vehicle, other than a bus, with any sign, poster, or other nontransparent material upon the front windshield, sidewings, side, or rear windows of such vehicle other than a certificate or other paper required to be displayed by law, except that there may be in the lower left-hand or right-hand corner of the windshield a sign, poster, or decal not to exceed four inches in height by six inches in width. No sign, poster, or decal shall be displayed in the front windshield in such a manner as to conceal the vehicle identification number for the motor vehicle when, in accordance with federal law, that number is located inside the vehicle passenger compartment and so placed as to be readable through the vehicle glazing without moving any part of the vehicle.

Then why are so many people driving around Ohio with their disabled parking permit hanging from the rear-view mirror, especially when the placard has this printed on it: "IMPORTANT: REMOVE BEFORE DRIVING VEHICLE"?