There is no reason why it shouldn't be simple.
Unfortunately judging by some things my colleagues have asked me, and similar comments I know the managers have received at both Northern and TPE, it strikes me that some Guards / Revenue Staff have no idea what a PTE area is, have no idea of county / ticketing boundaries, are incapable of grasping the difference between a CDR / SVR, and have absolutely no idea or interest in restriction codes. There are either a lot of very thick people employed, or a lot of people that make absolutely no effort to read nor understand fairly simple briefings, or they have all inwardly digested it but chosen to ignore it.
Sadly I can't find a head banging a wall smilie on here.