they are simply power outputs that each manufacturer has chosen to provide, they have nothing to do with the maximum power each brand can produce.
so less people buy the ford/fpv? lots more people choose to buy the hsv/holden? I sell cars for a living & i am yet to hear a marketing strategy of keeping a car less common from any manufacturer.
correct me if i'm wrong but you can beat the wishbone, the holdens which have macpherson struts did easily that's why they changed the rules so that holden have to fit the wishbones & make it more of an even competition.