I know that after school activities are unimportant and missing them wouldn't constitute neglect.
If the parents are as constantly drunk all the time as you say, I doubt every one of their needs are being met. They drink more than ever. The liquor store is even worried. Mom is in bed a lot. Days off are drunk fests. I just don't see how this is suitable parenting, and the kids have no voice, obviously.
I could be completely wrong.. they could be awesome parents. I find that very hard to believe. A lot of people 'talked' to me about my drinking, I later laughed about it as I was pouring vodka down my throat. Maybe it'll work tho..