That's how I shop with my three children, ages 1,2 and 4. When I stop in some sections they let go and pick up toys and things, but then it is right back to the cart. Sometimes my middle child will ride in the big part of the cart until it gets too full.
Perhaps the mom got distracted, I guess the boy was somehow climbing on the mirror, it came unhinged, any way you slice it, it is a tragedy. From the article, it could have all taken place in 5 seconds or less. No parent should ever have to bury a child, even if the child was doing something they shouldn't have. Just terrible, my heart goes out to this family and this little boy.
No they shouldn't. It's a grief that never goes away.