I'm guessing that the messages are tailored to whatever pushes the buttons the best. For example, if only one person has ordered today but it was 5 minutes ago, then show the "this product was last ordered 5 minutes ago" message instead of "1 person has ordered this today". Or, if there's lots in stock, then show the "you'll get this tomorrow" message.

I don't think it would be hard to make the messages selectively true.