Maybe they should be called the 5 gallon bucket brigade (that would be 19 liters in Hoser speak).
As far as I can tell by looking at the regs, there aren't any size or creel limits on Sunfish and a lot of places don't have any limits on Crappie or Perch. If there aren't any limits on the fish these people are taking, then they aren't doing anything wrong!
We have the 5 gallon bucket people down here too, and the thing that bothers me the most about them is that they let those fish set in those buckets for hours... with and without water in them. By the time they get the fish home, they're stiff as boards and have started the decaying process. I'm sure they still eat them, but that's just plain nasty to me! Buy a cooler and put those fish on ice!!!