My DH and I were just talking about this last night.
We saw this too. Not only is it illegal to have an open container in public where I live, but this is a night for the CHILDREN!!!! C'mon can't mom and dad put the drink down just long enough to make it around the neighborhood?
I am not against drinking in front of children, breaking the law in front of them is another story. People are just teaching their children to be sneaky and that it is okay to break the law if you are sneaky about it. Parents are also sending the message that you can't have fun unless you drink. Instead of trick or treating, guess what little Johnny will be doing in a few years on Halloween night.....ummmm DRINKING!!!!
Even if it is legal where you live, it is the parents job to keep their children safe that night. Not to become impaired by alcohol.
Just my $0.2