On another note: Shopping centres are geared for adults. Even to the point where they design displays to entice children so that the accompanying adults fork out money to pay for the merchandise. It IS an adult world, because especially in a retail environment, the children are not the ones with credit cards or EFTPOS access.
Which is why we should all relax a bit and remember that little kids are impulsive little people that quite often have no sense of reason. They need to learn from experience and by not taking them to places they won't learn boundaries or when to accept no for an answer.

I have spoken badly to and threatened a tantruming 5yo in a supermarket when reasoning and soothing didn't work. I have dumped a trolley full of groceries dragged him out to the car as well as carry a tiny baby over my shoulder and also trying to coax his little brother to follow me and gone home. It was harrowing and it took me months to get the guts to take all 3 boys out to the shops again!

We all have trying times, and yes only seeing a snippet of someones day could lead you to draw the wrong conclusion about someone as a parent in general.
Maybe instead of getting all defensive and taking things personally we could instead perhaps take it on board and remember to try and talk a little nicer to out kids