Yesterday, I overheard two Apple Store employees speculating with each other over what the Airport Extreme and Express actually do.
Those stores are full of bad employees.
I worked at my local Apple Store part-time, for a few years. I had some friends that worked there, the discount was great, and it was just something more productive to do after my 9-to-5 job than go home and goof around.
I'm a technical person. I loved when we had a customer asking about something weird in Terminal, a detailed VMWare/Parallels question, or the best way to re-do WiFi in their house. Non-technical employees would frequently grab me to help out with a technical customer.
I absolutely SUCKED with creative questions, though. Couldn't give you the first clue as to why one of your inputs into Logic is coming across too hot, or offer you any advice on what would help you improve your workflow in Final Cut. Need advice on Aperture Plugins? Uh, what? I'd always have to go find a creative employee to help me out with these customers. I'm quite sure I looked just as bad as an employee to those customers as the employees you saw talking about the Airports.
There were very few cross-over employees that were just as good with the technical stuff as they were with the creative stuff. And honestly, IMO, those employees with both skill sets rarely last long in retail, once they figure out what a regular job will pay for those skills.
So what you wind up with, at least in the Apple Store I worked at, were employees with different specialities. Some were cringe-worthy when it came to hardware, but were essential when it came to customers asking about the creative stuff. And vice-versa. But it worked. We all knew who the strong people were in areas we lacked in, and there was no stigma regarding getting help.
As for the employee in the OP up-selling, ... weird. When I worked there, we didn't get anything based up the value of the Mac that we sold. No commission, no spiffs, etc. There was no incentive to push a customer needlessly towards a more expensive Mac.