Also forbid other retailers from using plastic mock-ups of devices on display instead of the real thing. The iPhone is the only phone you can consistently demo.What? iWatch was released?
I think the training about products IS the key for using other retailers. Another point to this is, the employee happiness and quality. If the retail store employees are not happy, up to par with the technology, etc. that increases chances of having bad representation, which will kill the sales. Comes down to controlling whole experience and it is less likely if Apple starts dealing with more and more retailers.
I can't count the number of times I've walked up to a display excited to demo a new device only to discover it's fake, and worse, a cheap plastic approximation.