Paul Terry wrote:

Plus this is an area where evening and Sunday opening hours are tighter
than in central London so there will be periods when people simply cannot
buy an OEP locally.

What do people from, say, Epsom Downs do now when they want to travel
beyond their zones on a Sunday evening?

Well currently Epsom Downs doesn't have Sunday services or for that matter a
ticket office (the station building is now a nursery) but the other stations
do and the point does apply to evenings. In the old days the solution was
obvious - buy a permit to travel and sort it out on the train or the
destination. Now with those machines getting rarer I guess one just boards
with the season ticket and is expected to sort that out on the train or
destination. A sudden rule that before starting they must obtain something
that they can not always obtain is going to cause no end of problems.