It depends. Does the traveller genuinely know what to expect? The single fare finder is often broken when I go to use it, and its results are often utterly bamboozling when it does work. It's not easy to find if you don't know it's there. And you won't find anything obvious calling out to it at a station.They probably won't, but a sensible person should be keeping half an eye on their bank account or credit card statements and should see if something is out of the ordinary. If you were expecting to pay £15 and TfL have taken £35 you should notice that something has gone wrong, even if you don't know what or don't understand the technicalities.
If people aren't routinely checking their statements then that's on them, really.
If it is a genuine trial then there needs to be some sort of control, I suppose.
Now, TfL have made some meaningful improvements by actually putting up a poster at many London Underground stations, but it's still not very noticeable and the fares info table is very small, I think it's titled "Common fares from this station". In the case of Greater Anglia stations, I've never seen such a poster anywhere - can anyone enlighten me as to if they have put some up? I saw one for Oyster cards vs Contactless which was incredibly confusing and difficult to read.
All it needs to get this right is some big banners on gatelines directing people to the single fare finder online, a callout to it in the TfL Go app, and some UI improvements, especially around the bizarre text about London Overground services that it throws out. I believe station staff on LU can use their ipad to check fares. Staff at rail companies really need to be properly briefed on using the fare finder too so that customers can ask if they're not online, this isn't that difficult to get right but a lot of TOCs have overlooked it.
It would take very little work to give the transparency required for someone to easily compare what they've been billed to what was due. The actually difficult part, installation of hardware and development of the backend, has all been done.
