In the last year, I've been through over a dozen cities and used public transport in all of them. It is wild just how confusing and complex buying a ticket can be. While some cities obviously take a user-centred approach to ticketing, others appear to take a Kafkaesque delight in a bureaucratic maze of zones, apps, and intricate restrictions. One of the seminal texts in computer systems design…
Oh you’re right, I forgot that they changed the system for the RER. You used to be able to access the RER with a “normal” metro ticket as long as you stayed inside Paris, but for the suburbs you had to buy a ”destination” ticket which costed more or less depending on the length of your trip. I wasn’t certain whether that system had completely disappeared.
to be fair, i did stay within central paris. I’d heard the system had been updated as I described and I didn’t see anywhere to buy RER tickets but you’re right to call me out, i did post this without double checking :)