I think the most important question here should be "how best can we make public transport (including rail) accessible for occasional travellers" - i.e. complicated travelcard/season ticket/fare zone/fare band distinctions can be made simpler, and especially for shorter journeys, how to obviate, as far as possible, travel "obstacles" and complications (like long queues to buy a ticket/needing to have the right app for the more technology savvy travellers/needing to walk around with 5 different travel passes).
London in that respect seems to be doing a better job than many other places - in Paris for instance there is no means of paying for an "all-zones" train, bus, metro and tram on a pay-as-you-go basis from any place on the network to another. Whilst the Paris travel card prices beat London's by a large margin, it still doesn't make travelling easier, and, I think, may be a bigger obstacle than prices themselves.