Hidden Yarn Stores

Why is it that some of the LYS around here are totally hidden? Is this a common practice throughout the country or is just here in So.Cal?

Anyways today I went searching for Suzoos Woolworks. After a few wrong turns, I finally found the shop in a generic industrial park. The outside (and inside) isn't much to look at- it's your basic small shopfront in a long rectangular warehouse. Inside was a treasure trove of Brown Sheep, Berrocco and Crystal Palace yarn. They also had some really fun sock yarns, which is why this followed me home: