Would you put a $20,000 piece of shiny, brand new machinery in the hands of someone who does not know how to drive?
If you were a used-car dealer, would you put a shiny, refurbished car in the hands of someone who does not have a license?
If you were a dealer and you were financing your inventory by paying interest to a bank or to your manufacturer, like Toyota or Chrysler, would you take the risk that some unlicensed driver could hit someone and put that car that you are paying interest on every day in the repair shop for two weeks?
If you were a dealer would you take the risk that an amateur might have an accident with your car and if the cost of the damage exceeds 25% of the retail price, you will not be able to sell that car as new and you would take the financial loss, not your bank and not your insurance company?
Frankly I am surprised that they would let even an 18 year old, licensed or not, take a vehicle out, unless they are required by law to permit that.