That's so great that you were able to find a lesson out of the whole experience. It's amazing to see how God can teach us such wonderful things in such stressful situations.
As for people sitting and judging in stores, it happens and I think we have to just let it go. Those people who are judging, don't know what it's like to be in your shoes and while they shouldn't be judging, they still do. I find I have to readjust my thinking when I see kids screaming in stores at times too because my son is 11 and so it's been a long time since I had to deal with the stresses of a screaming toddler so it takes some self reminders and then I change my thinking and feel for the person dealing with the difficult situation.