"Rules like the one that allows people to not bother looking for work as long as they have a child under five are what creates bad feeling"
People? Or lone parents?
I worked full-time from the time when DD was three months old till two, then again aged three until four. It was hard on her. Everything was down to me. Working, dealing with bills and debts left by XH, phone calls, organising childcare, keeping on top of her clothes as she grew, nursey requests, cleaning, ironing, the shopping, cooking, birthdays, Christmas, repairs, decorating, even the logistics of taking the bins out and either dragging her out and it taking three times as long down four flights of stairs or leaving her in bed and praying.
I had no energy to spare when I was working and we weren't better off financially - and I was on a professional salary! When her health was so bad that I had to stop work, we went to parks, fed the ducks, I could shop around for bargains.
XH was gone and didn't contribute money, time or effort. I don't think it's unreasonable for a child who only has one parent, especially when it is not the remaining parents' decision, to have that parent around during their earliest years.
If anyone harboured bad feeling about me during that time, or resented a child with a life-threatening medical condition having me fully present and energetic during the times she was out of hospital and well enough to enjoy life with the other person in the world who gave a shit about her, well - I wish a whole heap of karma on their arse.