Istanbul has a card that you can use to pay for some things like public transit and have to use to pay for public bathrooms (because that's so cheap that if you paid with credit card, the fee would more expensive than the payment).

Maybe this is a way to break the credit card duopoly: offer something (like public bathrooms) that requires your card, and then try to expand it from there.

Many cities have rechargeable public transport cards.

Famous Japanese example: https://en.wikipedia.org/wiki/Suica

The plan:

  1) Build correct and cryptographically sound open protocol for NFC cash-cards
  2) Offer tech to public transport (as free open source)
  3) Boom. Millions of users of an open payments system