Why do all cars look similar/same/cloned now?

NASCAR of tomorrow: every manufacturers car must fit under the same template. I saw something like that when they were introducing them? also the low front, high back sedan is aerodynamic, has a huge trunk, good visibility and good safety. Thats why they all seem to gravitate to that design as well as the Focus/Prius/Veloster/Corrado/Dart/Genesis/*** fastback shape. So gone are the days of the long hood and low trunk. I mean look at a 73 Lincoln MkIV, or a Cordoba, or a 70s Grand Prix...huge cars with barely a back seat, terrible rear side visibility and a hood that you could put a putting green on. They were 'personal luxery coupes', I just call them bad. My Dad loved that style and with 2 sisters, we kids always got jammed in the claustrophobic rear seat. The Pontiacs were the worst, huge sail panels tiny little windows and high back seats as well as the SJ's almost bucket back seats. And of course he smoked...The cartoon cars were a breath of fresh air: PT cruiser, HHR, Scion xB, Cube, Beetle.....all gone.