I'd actually like to point out that you couldn't be further from the truth. I think your so called "serious tool shop" guy is just trying to justify selling his identical tools at a higher margin to cover his so called expert knowledge.
Apart from the budget brands (that for a home DIY guy work quite well) The Name brand tools are identical. Identical in every way. The difference in serial numbers is based on the country of purchase and I know for a fact there was a tool supplier in QLD who was fined for selling so called better tools at a large price but they were grey imports.
The main brands, Deawalt, Makita, Bosch in Bunnings are the same as anywhere else