How Should Parents Take Care Thier Children In The Stores?

Kids can cause disturbances in stores, running around, damaging the goods for sale, knocking over old ladies, etc. Etc.  It is best if parents firmly teach them to be calm and well-behaved. HOWEVER, others can become far too impatient and judgemental of parents of kids running around, not knowing what is going on in their lives and not fathoming how difficult things may be for them.  We non-parents especially can be brutally (arrogantly?) judgemental.
An example: My friend's son was a huge baby, so tall at age 2 that he looked like a 5 year-old boy.  It turns out that he is also mildly autistic, which in his case means virtually uncontrollable.  People in stores reacted badly to this wild out-of-control kid who looked almost school-age and acted like, well, an uncontrollable 2 year-old.  His father worked out-of-town for weeks at a time, leaving Mom alone with the wild child, and they had no trustworthy family members who could babysit the kid.  So they had to go to the grocery store together or go hungry.  As this mother helplessly chased after her boy in the stores, people frowned, they sneered, they told her to take control, they made harsh comments.  She felt horribly embarrassed.
Let's keep this kind of situation in mind before we react with judgement.