Genki 19-2 Giving Respectful Advice

You may hear the "お + verb stem + ください" form in public address announcements and in the speech of store attendants.

Although such sentences end with ください, it is better to consider that they are (courteously phrased) commands, rather than requests. When someone tells you お〜ください, you are being encouraged to perform actions for YOUR OWN GOOD

If you want to make a request, use this form instead.
しおをとっていただけませんか
Would you please take the salt (and pass it do me)
けーきをもってきていただけませんか
Would you please bring me (a piece) of cake