Everytime I see kids acting up in public, I don't think look at these out of control kids. I think look at these out of control parents.
Do you think some parents are oblivious to bad behavior?
I'm thinking of buying a video camera to record them behaving badly in public.
Some parents definitely don't care. It's impossible to control how your child behaves all the time, though.
I'm going get the parents good. I'm going to show them the video and call them out in public.
You might want to be careful about calling them out, sometimes it is hard to control your kids 100% of the time and people will think you are bullying the parents. It would be good to  ignore it unless it gets dangerous.