Why do people do this?!

So a guest said they were on their way for DU. one bag, 15 mins away, easy enough to prep. An hour goes by...then two...they're down to 9 mins...then suddenly BEEP BEEP! they're here, and I'm taking care of returns at the desk on the opposite side of the store....so I hurry down to deliver it, and as I'm walking back up to the desk I see 2 guests walk in...THE SAME ONES I JUST DELIVERED TO 1 MINUTE AGO 🤦🏼‍♀️🤦🏼‍♀️🤦🏼‍♀️🤦🏼‍♀️if you're gonna come in anyway, why not just pick your order up inside??!