[mriou]

Banks are made of a mess of different systems. Some are locally ACID, but overall reconciliation and compensation are what keeps it all together.

Regardless, this has little to do with banking. The systems are too widely different to be compared productively. The only conclusion you can get from this (marketing) story is that when you have an eventually consistent system, you will need occasional distributed locking. Cassandra often comes in pair with ZooKeeper.

The other conclusion is that no matter how trivial they sound, distributed transactional systems are far from trivial.