At least when it comes to food, a small selection feels curated, as if the grocery owner is vetting this food for me and saying "These are the jams I find worth your time". A supermarket with 8 brands and 38 total selections didn't take the time to help me. I suppose it's like when non-techies walk into Best Buy and there are 40 laptops to choose from, ranging from Atoms/Celerons to various i7 types. We have all done it before on the phone: "anything but the Celeron... yes it's cheaper... but it's slow, just don't get those" - basically we narrow down the selection significantly by saying "at least 4GB ram, i3,i5,i7".
The analogy is not perfect because there's a big price difference in laptops. But making the consumer feel "safer" with their choice by eliminating the really bad choices up front lets them shop worry-free. This small selection thing can be bad too, though - I for one hate shopping at Walmart because I know without a doubt that whatever I am purchasing is the absolute lowest common denominator in terms of quality. They might have 2 different types of lawn chairs, and you better believe that both will fall apart just after the 1 year warranty is up. It all comes down to trust; if you trust the store in their selection, you'll enjoy shopping there.
Indeed, this point came up in a conversation about Whole Foods. Sure, they are often overpriced, and you can find many of the same brands and products in other stores, but by shopping at Whole Foods, you can at least have confidence that any random product on the shelf is at a reasonably high level of quality.
The analogy is not perfect because there's a big price difference in laptops. But making the consumer feel "safer" with their choice by eliminating the really bad choices up front lets them shop worry-free. This small selection thing can be bad too, though - I for one hate shopping at Walmart because I know without a doubt that whatever I am purchasing is the absolute lowest common denominator in terms of quality. They might have 2 different types of lawn chairs, and you better believe that both will fall apart just after the 1 year warranty is up. It all comes down to trust; if you trust the store in their selection, you'll enjoy shopping there.