The salesperson could have convinced the grandmother to buy a "Sinclair iPhone by Timex", assuming it was packaged into something roughly phone-shaped. The problem here isn't the appearance of the product.
I will happily point the finger at any tech giant when it does wrong, but Samsung didn't do anything to warrant years of court battles and accusations. It's tiring to hear people defend Apple's sideshow legal agenda.
The "touch screen phone" was inevitable, and was always going to be something with round-ish corners, flat, with icons. The shape is too fundamental to the ergonomics of such a device. There's too little room for difference in design, relative to the objective of making such a device comfortable to hold. I had the Nokia N9 for awhile, and the pointy/squared corners were not a great feature. They probably wanted to avoid rounded corners, which is a ridiculous situation where consumers lose out.
It's flawed logic to say it's a widespread problem that people "accidentally buy a Samsung" because a salesperson lied to your grandmother. That's an edge case that means nothing.