> Appearing confident rather than actually being correct is probably good for closing sales and for short-term customer happiness, but it's no good for the longer-term

Well, that depends--and that's where my metaphor breaks down. The customers went home satisfied and remained satisfied (at least, that's what their consistent repeat business and smiling faces would suggest).

Tomatoes and website loading times matter to you in the here and now but don't have any lasting effect on your life. That's not the case for making a major purchase.