I work with SS with childen in care. of course SS has lots of expreinece with addiction problems.
There are support services SS will direct people towards them, they are somewhat limited and very dependent on peoples commitmemt to engage, which is often, paticuarly in drug cases not consistent.
AS you say SS will then give parents lots of opportunities to try to demonstrate they can care for thier childrem, this is montoring and assessment work, the bulk of what they do.
The idea that there are varied and extensive support programmes that if told about them people will engage with and commit to and that if they engage they will be successful, is just a little naive.
Things often just aren't that simple for people struggling with layers of psychological problems and drug dependency like KK.
SS try their best and have some success, but ultimately their job comes down to a tough decision, can this person care for these children, are they better here or in care, can this person maintain change in their life etc etc.
I'm glad you're experience has been good, for many people it is, I hope KK eventually gets help and can do what she needs to do.
It's just not always that simple is all I am saying.