Richard M Willis wrote:

That's the reason it's not being rolled-out so quickly onto NR: they
are waiting for OysterNextGen where the cards can be read at a distance of
several meters without a touch in/out and without the passenger knowing
they've been read. In this way, they can check for invalid routings if
wanted.

I rather doubt this.

There were some trials with high-power readers on the current system,
but I heard it was causing the wrong barrier to activate so wasn't
practicable. Might have been an urban legend, though.

However, as someone else here has suggested, TfL seems to be getting rid
of fare evasion by engineering it out of the system

Which is the best way to do it. The paper fare structure is not
well-suited to Oyster.

I expect that NR validity within the Zones will be accompanied by the
integration of the NR and LUL fares structures within the Zones (a true
Verbundtarif), or at the very minimum a simplification of the NR fares
into a pure zonal system.

Neil