The issue here isn't whether kids get into mischief. The issue here is the mom suing the manufacturer.
I don't think the manufacturer is culpable in the death, but it is clear that it looks like a design change is needed. This death was tragic, and preventable.. even after the actions that wound up with the child in the machine... That is undeniable.
Just like escape latches for trunks, and no longer locking refrigerators... an over-ride shut down and unlock should be part of the design of these things... and hopefully will be.