If you have a direct way through the private land, maybe even fenced to both sides if you feel threatened - then this would not be a issue here.
But irresponsible people are a general problem. Often it is just mere ignorance, though. Many people simply do not know for example how to .. go to the toilet in a forest. Even when you do not have a shovel with you, with a wooden stick or stone, one can make a hole deep enough to cover all of your buisness. And suddenly all the trees next to the major walking paths would not be covered in shit and toilet paper anymore. And that you do not drop your garbage wherever you stand, is a deep rooted sociological problem. One for me starting with the stupid smoking ad campaigns, where the cool cowboy flicks away his cigarette. And where it lands, the plastic will remain.