Too Young to Babysit??

While Dominic goes to his music therapy class there is an area where you can wait that has a few tables and chairs and is where I hang out.  A few weeks ago, I noticed there were four small children by themselves in that area.  At first, I thought they were with an older woman who was also sitting in that area.  Nope, they weren't with her.  The kids were pretty well behaved for a while and then they starting getting really loud.  When the littlest one fell on the ground and started crying, I asked the oldest child (she looked about Dominic's age, like 9 or so) where their parents were.  She said, "oh, my mom is upstairs."   The older woman and I were kind of watching this little girl take care of her three siblings.  She was entertaining them, taking them to the potty, etc.  The entire time that I was there, I never once saw a mom or dad come down to check on them.  I was thinking that it would probably be okay if she was watching her siblings at home by herself, but to be in a public place, seemed I don't know, dangerous?  The front door to the building where this waiting area was is close to the front door.  There is a receptionist area you have to pass by, but still, something about the whole thing seemed wrong to me.  The older woman that was watching these four kids told the oldest child, "you're a really good babysitter."  She definitely was - she was extremely mature. It seemed like an awful lot of responsibility for a young girl to be watching three younger children in a public place.  When Dominic was born, Lauren was about 8.  I would make her keep an eye on him when I took a quick shower, but that would be about 15 minutes or so and we were in our own house.  In hindsight, I wished I would have said something to the receptionist. I'm curious as to what other moms (and dads)  think of such a young child babysitting that many other kids in a public place.  Let me know your thoughts!