Its a horrible story, poor child.
But (and its only a little but) - I work with women who can't read. I teach them to read! They can't read the dosage instructions on Calpol. They can't read the instructions for making up formula (and yes, most of them ff). They can't find out when the library is open. I taught one young woman who was so innumerate she had trouble reading the doctor's phone number and dialling it! Every time here baby was unwell, she dialled 999 as it was all she was able to manage.
One third of first time Mums in Glasgow are unable to fill in the prenatal questionnaire that the midwife gives them and also can't do their child benefit form. Functional illiteracy.
So while this is something that should never have happened, I suspect (and I also used to teach in Edinburgh) that you are looking at people who are sadly unable to access any information at all. To you and I it is obvious you don't give a child methadone. To other people, who live very chaotic lives and can't communicate properly, not so obvious.
I'm not defending them and Social Work should most definitely have been more involved before now. But I think it is very hard for people using a site like MN to understand the sheer chaos of some people's lives, and also the isolating factor (which I am not saying was the case here) of not being able to read and count which may have contributed to this.
I hope this poor baby is in a safe place now. But I think that there is a lot society can do to support women in this kind of situation, and that more shoudl be done. I'm so proud of some of the women I am teaching - one of them who couldn't read at all 3 years ago just sat her Standard Grade English adn Maths!