Unfortunately the trouble is US. Most of the lands were probably open at some point until some fishing people showed up and when they left their trash did not.
It does not take long for landowners to spend time picking of what others left before the posted signs go up.
This isn't the issue there. It's people wanting their own private fishing and just plain ole greed I guess. Even on the public water you have to be careful. We were getting shot at right where KVD and those guys fished the classic in New Orleans a few months before they showed up. If you can get there from a navigable body of water it should be public. My buddy's family has a private lake up by fork that is well managed and hardly fished. There's a very small creek that runs into it from somewhere else that evidentally you can get a duck boat or kayak in. Some guys showed up out there one day fishing and they didn't know where they came from. Not that they were all that mad but just curious how they got there, because the ramps are all behind locked gates. They asked the game warden after that what the deal was and what they could do. He said as long as they remained in the boat the whole time on their way, while they where there, and until they were off their land they were legal. If they had to drag the boat around obstacles or anything made them get out of the boat on the way there, or if they touched the bottom of the lake it would make them illegal.