Nope - still no justification.
What the mother did was wrong, plain wrong. I'm not saying anything to the contrary and i'm not justifying it!
"I'm seeing it as justification, when you say for all we know the mum is at home and feeling shite. "
This is not justifying. This is saying that the mother may be regretting her actions and feeling shite for doing what we all know is wrong ...
What lead her the shouting is something we can only speculate on, because as you rightly say, we don't know
Chances are that she's regretting it, chances are she's not. What happened was wrong, but we don't know what led to it. That is the point that i am trying to make. It may well have been the last straw for the mother after a really shitty day, that does not mean she was right nor does it justify her actions in any way. It may help to explain it somewhat though, no?
I totally agree that this is crappy parenting, but people in glass houses and all that ...
Those of you who have never raised your voices to your DC's, my hat is well and truly off to you.