In the UK, who is going to take overdue action if an aircraft doesn't turn up at a private strip ? I don't believe there is anyone monitoring Flight Plans for such flights to make sure they are closed, is there ? It's up to the pilot to arrange for a responsible person to look out for them and raise the alarm if need be. That person will do so whether a plan is filed or not, and whether a filed plan is open or closed, regardless. For that reason, I don't see it as a big safety issue in the UK since I don't believe the mechanisms exist for monitoring arrivals and matching them to filed plans at landing sites where there is no ATC or FISO presence.