Is Shell That much Better?

In Las Vegas (Lamb Blvd) there is a Shell gas station selling gas for $3.49 a gallon.
2 blocks down the street, there is a gas station selling gas for $3.19 a gallon.
There were 5 cars at the Shell gas station and 3 at the other station.
The gas comes through the same terminal about 5 miles away.
Is Shell gas really worth 30 cents a gallon better than the other store or are the gas shoppers just stupid by not looking down the street?
I honestly don't know.