Your hands get full
So you go into The Container Store, and you think you only need an ice tray, so you pass up the baskets and shopping carts. You grab your ice tray, but you see a sign further back for a sale on office storage. Before you know it, you're holding four items and your hands are full. You can either a) go to pay, or b) put the stuff in a shopping cart and continue shopping. Which do you think the store prefers? The Container Store has figured this out by brilliantly locating a line of carts at the very back of the store. It's the same reason clothing salespeople ask if they can start you a dressing room - to take all those clothes off your hands. This is a push for higher sales, disguised as convenience! Nice job, guys.