the simple answer is that users can add any taxon to checklists for places and add establishment means for them. In this regard, Homo sapiens is no different to any other taxon in iNat, and it can be added to any checklist and have its establishment means edited. This is what has happened here in all the cases mentioned, and you can see who made the addition by checking each checklist. So for eg Poland like in OP’s screenshot, it is because a number of years ago, a particular user added the species to the Poland checklist, and then explicitly set the establishment means to introduced.
perhaps staff could ‘lock’ Homo sapiens from being added to place checklists