Not being a street vendor, I’d guess that you: A) definitely don’t want to leave a smartphone someplace easy to check B) don’t want to take the time to unlock

Not being a street vendor, I’d guess that you: A) definitely don’t want to leave a smartphone someplace easy to check B) don’t want to take the time to unlock your smartphone to see the notification C) do want something that can notify you without taking your attention away from three other customers