I'm not sure about this parable; it reminds me of Chesterton's fence. Our optimistic salesman may be completely ignoring the fact that no one is wearing shoes because no one needs or wants to.
Isn't that perspective represented by the first salesman? Both are seeing the same limited data and drawing a conclusion about business potential. The second salesman may be wrong, but their optimistic view is still a possible one.
Especially since we know shoes can be plenty useful in hot climates and are 99 percent about fashion anyway.
Now I have a name for the tendency of bad supervisors that show up and announce "Things are going to change around here!" before they have any idea why things are the way they are.