This is because most of the people who book the cars dont actually need them! they book a car for investment purpose only, so when the delivery time is up, they refuse to take their vehicles from the showroom until they get a 'genuine' needy buyer, who is forced to pay the OWN. This may be the reason why these showrooms have more than enough cars still waiting to be delivered!!!! and they dont even have space to park them.
Normally most of the showroom persons are involved plus many of the investors, who use to invest in other areas such as property... earlier, now invest in booking cars these days. When the delivery time is up, they prefer seeking a higher OWN value until they get the desired one... Showroom people also have some commision in this whole scenario!
So in this way those who need to buy a car are forced to pay OWN as the actual lot is already occupied by the investors.
anyway its something which is NOT good at all and should be DISCOURAGED by the masses.