Well, given that Life-Like didn't have a PS-1 model of their own, they used the closest model they had. Aside from the diehards, most people are not as particular concerning whether or not there is/was a prototype for a model. And tooling has to be amortized. Life-Like never released a prototypical scheme on the N scale Evans car, just as RivaRossi never did on their 40' chemical tankcar and AHM never did on their 3500pd Flexi Flo covered hopper.