in my experience society does give the mother an awful lot of leeway
I disagree. As a society there is no respect whatsoever for the single mum. If she works, her children are neglected, if she doesn't work, she's benefit scrounging scum. I have lost count of the number of people I would consider educated and decent who at some point during my many years as a single parent made frankly disgusting comments about me, to me, and within my earshot. These range from 'I suppose we're paying for you to live here' said in front of my children (I own my own home, outright, no mortgage), to 'you really need to get your child's hair cut because people think you can't cope' (from a woman who's sons have hair down their backs!), to 'I wish I could do what you do (I am a teacher) but I can't because I have a husband' (well, no, she couldn't because she isn't qualified, not by about 6 additional years of education). I have heard people discuss my 'poor children' within my earshot because I work for a living and 'she's always putting them in childcare, why doesn't she just think of her children?' to 'she was at the pub last week with a man, how disgusting, I suppose her children will have another uncle soon' (I have had a number of boyfriends before meeting my partner, my partner is the only one who I have ever introduced to my children)..... someone even said to me once 'why aren't you sad? If I was you, I would be so miserable all the time'. Oh and the classic 'you should send your children to live with your ex, he's a good dad, they would be better off with him. You shouldn't have a career, you're a mother. Your ex's girlfriend would be such a good mum for them, she doesn't work, did you know that?' I mean, seriously, what the actual fuck was that about?!!!!
And don't get me started on colleagues who have no shame in saying 'well, his mother's a single mum so what do you expect?' in relation to any child who's behaviour might be less than perfect in school.
Women are blamed for everything 'bad'. Yet is is women who stay, who take responsibility, and bring up their children as best they can making the best possible decisions they can for their circumstances. All the bad in our society is our fault. And yet we stand by men, laugh alongside them about the psycho ex, agree he shouldn't have to pay maintenance because she works/doesn't work, and stand by him when he makes a decision to abandon children in favour of a new partner.
My comment further up thread was responding to how we change things, not to somehow further pit mum against step mum. I think that's a different issue altogether.