Children should be told the truth from the age they can understand so 9 and up depending on the child's maturity. That way lies and manipulation won't happen.
Adult children who do this to the parent who stayed and cared are ridiculous. I would go nc with my own children if they did that to me.. Well maybe not but I would be very upset and disappointed.
Mothers who don't tell the truth do their children a wrong in aiding the other parent, to keep up a pretence. Sorry but if the father does not want to see the child then the worst thing to do is to keep chasing them, as your child is not stupid and they will know it is forced contact.
It's better to be a strong parent and to be both mum and dad for your child.. It more of a protection from being let down and knowing that your dad can't be bothered to do much with you.
You as a mother need to mitigate his uselessness and say to your child he does not want to be involved, it's not you and it is him. Children do understand and whilst sad, it's better then having half hearted contact just because society feels the mother should do so. It's not in the best interests of the child.
The child's best interests is to have two fully engaged parents, if they have one then that's good and better as forcing the useless parent usually just causes more damage.
Same applies to maintenance, children know who pays for them. They really do from a certain age and if he never steps up then yes its tough but you need to just get on with it.
There should be more societal pressure but since women can be the worst for shaming women who go for maintenance or say things like "well be happy you get £40 per weekas I only get £10", nothing will change.
The attitudes in the UK need to change and its one thing America does well. You can go to prison or face fines and the debt follows you for your whole life as a priority debt as it should be a priority.
The UK makes it too easy to dodge paying and men and women back up the non payer. Why would a woman choose to date a man who does not pay for his children?? Yet this is the norm...