One of my favorite restaurants is a little Mexican place in Utah called El Chubasco. I've often eaten there twice in a day, and once (it's true) ate there three times.
It's always crowded. Sometimes people wait outside, in the cold, even though there are plenty of alternatives within walking distance. So, what's the secret? Why is it worth a drive and a wait?
No specific reason. The energy of owners Jill and Craig is certainly part of it, but most customers never encounter them. I think it's the hand-fitted gestalt of thousands of little decisions made by caring management out to make a difference. Usually, when a business like this gets bigger or turns into a chain, marketers make what feel like smart compromises. The MBAs collide with the mystical, and the place gets boring. "Why do we need 14 free salsas when we can get away with six?" or "Perhaps we ought to stop handing out huge tumblers of water for free–our bottled water sales will go up."
This turns out to be the secret of just about every really successful enterprise. Sure, you can copy one or two or even three of their competitive advantages and unique remarkable attributes, but no, it's going to be really difficult to recreate the magic of countless little decisions. The scarcity happens because so many businesses don't care enough or are too scared to invest the energy in so many seemingly meaningless little bits of being extraordinary.