> But everyone mostly pays a flat rate for using the whole system each week (within the zones they travel to at least).

I was wondering how widespread travel cards are, since I never bought one personally. If you don't travel much on the weekends you end up paying more.

In 2017 TfL sold weekly, monthly, and annual travel cards covering year-round flat-rate travel for ~0.8m people. Travel card journeys account for about 39% of all journeys.

Maybe it was more common in the past, since travel card journeys dropped around 10% a year from 2015-2017.

https://tfl.gov.uk/corporate/transparency/freedom-of-informa...