There is no way I could keep a look out for a toddler in this situation because my view is blocked by my purse and the items in my cart. I'd have to move my body from behind the cart to the side so that I could look in front of it, and my head from eye-level to the floor.
And, while I'm moving my body from the back of the cart, I'd have to make sure there was no one coming up from behind me so that I'd not be hit by their cart.
LeeveeWoman, I'm not disagreeing with you - I'm more addressing the comment that, when you're moving, you're always looking straight ahead of you. That's not how people shop. In fact, I'd be willing to bet that everyone is shopping pretty much the same way - when they're moving, they're also looking at shelves (not with tunnel vision to where they don't see elsewhere, but still not always looking straight ahead of them).
It's the same thing when you drive. You don't constantly look tunnel-visioned straight ahead of you. You're looking at cross streets and signs and the rear-view mirror, etc. That's not to say that you barrel into other cars ahead of you - of course you're looking at what's in front of you. But you're also looking at the street signs to see if this is where you turn right or whatever.
Editing to put the quote in that I was referring to