The purpose of the mobility carts is to help people who have difficulty walking around a Walmart store themselves. For the majority of children, that isn't an issue. They're bursting with energy, and they can run all the way around a store five times before we even have a chance to get around it once. If they over-exert themselves, though, then you run into an issue. Your child needs to nap, and there's nowhere to go for them to put their head down. That's when you have to think outside of the box, as this clever shopper has done.
When his child decided that walking alongside the cart was more effort than they were willing to give, he's just trussed their feet up to the back of the cart, and decided to pull them along. That thick coat is providing enough protection to stop him getting bumped by the floor too hard - although he's going to have to keep a careful eye out to make sure nobody stands on him.