Are you looking for drugs in a parked cruiser on the side of the road? Those laws are in place so the police can see into your vehicle to identify what is in there.
If you're tinting your windows to the point of being blacked out (that nobody can see in) then expect to be pulled over and talked to by the police.
The main reason for that law is so the cop can see whether or not the person on the other side of the window has a gun pointed at him.