In the good old days of Group A and N a manufacturer would have to build 5000 copies to homologate a model for competition. Unfortunately for us mortals that is no longer the case and bargain performance cars like the big boys play with are a thing of the past.
The only reason that you see so many WRXs, Evos,Cossies,etc. is because they had to dump a whole pile of them on the market in order to compete with them. Now all the do is make team cars in the case of the WRC cars, and the minimum number of kits as in the case of S1600.
You never saw a street version of the Peugeot WRC, Citroen, Skoda etc.. The Subaru has been a WRC car for a few years and the last manufacturer to hold out was Mitsubishi who only last year decided to go the WRC route and are now out of the WRC for a year.