That's not the opposite question at all. Of course different products are made better than others. It's the basis for why there is a cost difference. We aren't talking features, we are talking basic quality.
Anyone who is involved in specifying manufacturing parts and processes will tell you the same thing. Better parts and raw materials cost more. Better processes cost more. Better people cost more. So the finished product costs more and for that additional cost the consurmer can expect it to do the same job longer and with less downtime.
As far as dealer markups I have no real knowledge. I would think that they would all be about the same percentage but that is just a pure guess.
rScotty