All US cars have heated and electric mirrors because that is standard in the US. For this reason all cars have the plug next to the rollbar for the defroster that prior to 2003 was used only for the hard top. You still have a working plug even if the car did not come with a hard top, and of course the dash button is there on all US cars.
The early ROW cars are different. Heated and electric mirrors were an option. If you did not have the option then you had a manual adjustment for the mirrors and no button on the dash for the heater. However those cars are wired for the defroster, but you need to add a relay and the dash button.
http://www.renntech.org/forums/index.php?showtopic=3959&hl=trivia