>I wouldn't judge and assume that it's because of a glaring moral failing.
It's not a moral failing by itself, but it then suggests "how many other activities are cut out because they can't take their eyes off their kids for 30 seconds?" That behavior seeps into the rest of the going ons in life.
That's not bad, but I wouldn't be surprised if that becomes the type of parent who cuts all social contact with non-parent friends after having a kid.
But what I'm offering is that if I saw a parent leaving a cart, I wouldn't judge and assume that it's because of a glaring moral failing.