Most shops in my area teach. People are likely to pick up a few items when they come in for a class (tools, snacks, tubes, patch kits, etc.). I used to work for a shop right next to a rail-to-trail and we would repair tubes for free (lots of punctures due to thorns and sharp rock on the side of the trail). The profit made on patching a tube or installing a new one was minimal when compared to the goodwill / return customers. If someone wanted to fix their own tire we'd let them use our stand, pump, & levers.