Letting kids run wild

I work for the court system. I have parents who bring their kids—usually 4 or 5 year olds, sometimes older—with them when they come meet with me. I have no problem with that—I have an 8 month old so I know how it is. However, one thing that really irks me is parents who will let their kids walk all throughout my office, pick stuff up off the desk, knock stuff over because they’re “playing with it”, etc. The parents will sit there and just say “oh honey, don’t do that” IF they say anything at all. Just Friday, there was a parent in my boss’s office who was letting her 4 year old run throughout the building from office to office. She came behind my desk and started grabbing stuff, then went to my coworkers office when she wasn’t even in there. I had to ask whose child she was. The mother had to yell for her daughter when it was time to go. I couldn’t imagine letting my 4 or 5 year old run wild like that. There’s this thing called manners and respecting people’s belongings/spaces. Do you teach your kids about boundaries, or do you let them run wild? What would you have said to this kid?