I think it's more about the type of store. I was with acquaintances returning clothes at high end stores (meaning: expensive) and service was great. I would not try that at a low end store (meaning: cheap).

From my point of view processing a return costs the store money. If they don't make a high margin they will (try to) discourage it. If in US everywhere they are fine with it for me it means they make higher margins everywhere.