I used to ref 1st through 6th graders at the local rec center.
It was a lot of fun because we had a teach first policy that allowed us to blow the whistle to stop the game, explain to the kids what they did wrong and what they need to do to play correctly.
They usually got the ball back if it was a traveling violation, double dribble, or carrying the first few times, but after that it was by the book with explainations to the kids every time until the understood. Coaches loved the system because we always got the kid's undivided attention.
You wouldn't believe how fast they picked up on the rules when if was explained to them. By the 3rd week we didn't have to worry about the stuff you described because most of them knew the rules. It was a very easy job after that.
If the refs were letting them get away with it, especially without explaining the rules, they will never learn correctly.