Dealer's in and out is the same as rental car co's in and out

The mileage reading on odometer when dealer received the car is "In", that when it is out (sold) is "Out". Technically the out is always greater than in as only the car has been moved. Ten when "in" can equals to "out"? Only one case that the dealer had never moved the car (dropped the car on ground and the car parked on that spot ever since). "In" greater than "out" is definitely wrong, intentionally or unintentionally.