Well, that’s an interesting development. I would imagine Cuffley will go the same way at some point, although more people probably use Epsom than Cuffley.
Both stations are part of a growing list of places where there are different caps applied when using contactless compared to Oyster. If you use an Oyster card to these places then you will be capped at the Oyster zonal rate (not always zone 9) because that’s all Oyster can do. The adult fares get put through the back office later, but I’m assured that it won’t retrospectively increase the charge. However, when using contactless you will be subject to the contactless caps (which aren’t always more expensive).
This is a consequence of the political desire to expand Oyster to places where the cap structure did not match the travelcard prices already in place. When they finally get round to allowing discounts on contactless PAYG I fully expect Oyster to be discontinued at those places.
I think I need to look at documenting the arrangemnets at these dual-capped stations shortly.