As one of the guys who used to work at a dealership, I can honestly say, cars did get lost sometime. When they are covered in a lot of snow, they can be easy to miss among hundreds of others when you're flying down the aisles looking. And sometimes, someone forgets to put the stock number on the mirror to find them easily making it even more annoying. Keyless entry helps, though. But lots of snow can hide flashing lights
Long story short - its easy for a car to go missing for a little while.