I can’t find anything that says these parents knew she was at a rave. My parents never called in the middle of the night when I was at a slumber party; they never had reason to. If these parents never had reason to before, how are they bad parents when a 16-year-old decides to do something stupid? Teenagers do have responsibility for their decisions.
Their brains aren't even done growing. The law won't let them sign contracts. You know this, right? Ever heard of parents "raising" their kids. Checking on them and making sure where they are and what they are doing...the duties of a parent?
I'm afraid your attitude is the common one now days.