Paul Terry wrote:

It's not really that difficult. People have managed for years to
understand that an extension ticket is needed to go beyond their
travelcard zones.

Yes but Oyster has been advertised for (slightly fewer) years as a flexible
system where one doesn't need to faff in queues before starting the journey.

And if the level of publicity about OEPs at stations served by SWT is
similar to National Express ones, how is the layperson going to hear about
OEPs?