NOT SO LONG AGO, being reasonably trustworthy was good enough. But soon only the extremely trustworthy will thrive. If you accidentally try to order the same song twice from iTunes, you’ll be warned that you already own it. Not because it would be illegal or unethical for Apple to profit from your forgetfulness. There’s a clear business reason: The leaders of iTunes realize there’s no better way to make you trust them than to be totally honest when you least expect it.