She left it open on the kitchen table.

Actually, we don't know this. The things on the table in the article are the mechanism for production of cannabis oil, not the cannabis itself. Furthermore, we don't know that it was even being stored. She was raided, and we don't know the details of this. Was the apparatus out because she was actively making some at the time, while her kid was at school and thus away from the production? I mean, that makes sense, and requires no less assumption than your assumption that she's irresponsible.

Even if it wasn't in storage, there is no storage short of locking it up that makes it unable for a child to get to. There's no moral difference in my eyes between leaving it on the table and leaving it in the fridge, either way if the child wants it, they'll get it.

Also, the kid admitted that there were adults in the home, friends of the family I assume, that would smoke.

Well, last I checked you would use a product such as this indoors. Do you expect them to have cannabis and then never use it? I mean, the beers in the example I gave are also used indoors by adults. Is that no the purpose of these items? Should we also take kids away from those who say "Adults, including friends of my parents would come over and drink in the house," because that's what you're saying to continue the comparison.

Basically, you're two "fact" don't show anything about responsibility.

But she is clearly irresponsible and she deserves some kind of repercussion to be more careful about her marijuana use when living with a child.

Well, I'm glad that you're here to judge her and make her and her child's life a living hell to satisfy your desires. You're making assumptions that we don't have and advocating using the force of the government (which is to say armed men and force) to teach your lesson.

If that's acceptable to you, you're the only one that has to sleep with your thoughts, but frankly, advocating messing up families, even if it doesn't involve taking her child, to teach moral lessons that are debatable is incredibly questionable.