Thanks for the explanation! Regarding the storing value on the card, one notable deployment that does work like this is the London Oyster card. These were first

Thanks for the explanation! Regarding the storing value on the card, one notable deployment that does work like this is the London Oyster card. These were first rolled out in 2003, so getting a reliable internet connection everywhere they were used wasn't possible. When you topped up online (I haven't lived in London for a few years, so don't know if it still works like that) you had to select which station your top up would be applied to, then overnight that station would download a list of topups, and apply it to your card when you touched in or out next. So at the time there was no real time connection to a centralised database.