Most manufactures offer to down rate the GVWR on the newer 3/4 and 1 tonnes because in Ontario going above a certain GVWR results in more expensive stickers and other headaches. It's not that those trucks haven't gotten better its that the Ministry is still very pig headed. With the 1/2 tonne stuff I think half of it is consumer demand and the other half materials and engineering. I wouldn't call it stronger per say as HD trucks are going to fair better in the long run when you work them hard vs. a 1/2 tonne, but 1/2 tonnes are certainly more capable than the once were.
As per salespeople I agree to an extend. Absolutely some will try to sell you anything to get it off the lot, but also imagine trying to know every detail of all these different tow rating variables, as well as having to know the fuel economy of the focus vs. fiesta, the truck space of an edge vs. and explorer, which trim levels of fusion have bluetooth, and a million other trim variables and specs. Downright impossible and many consumers will want answers on the spot not "let me check the brochure".