Helen Deborah Vecht wrote:

(snip)

Cash fares are for losers and you should have some sort of PAYG Oyster
before you come to London.

A concise and to-the-point summary - I like it!

(snip)

Download next year's Fares leaflet from the TfL website, get confused &
exasperated, then make up your mind...
(snip)

The problem comes when people find the whole Oyster system so confusing
that they give up on it before they've even tried it, and end up being
a Oyster-refusenik loser - and with that quite possibly become a
complete bore as well when they whine on about how it's all too
expensive/complicated/was much better in the good old days
(conveniently forgetting intermodal ticketing didn't exist!).

When Oyster Pay-as-you-go rolls out on National Rail across London then
it will at least remove one major point of confusion.