> This data store is the system of record in their credit card authorization and billing pipeline, and so it has extreme consistency requirements.

This seems like an odd requirement to me. What are the use cases beyond a few minutes past the end of the ride?

- Reconciliation of Uber's finances. This definitely needs to be correct and consistent and maybe even auditable, but it's also done at the end of any given billing period. A daily roll-up would be sufficient.

- Showing each driver and each rider their own history. This ought to be fully correct (especially for drivers), but it's a massive double-edged sword. Uber's app, for example, appears to be entirely missing the "please forget my ride history" button. And this isn't surprising: Uber apparently stores it in a ledger, fully indexed, complete since at least 2017, that is cryptographically immutable. Is this actually a good thing? What happens when a privacy regulator tells Uber to expunge, anonymize, or pseudonymize old data?

- Handling chargebacks? Having a high quality record going back 180-365 days seems useful. But the cost to Uber of occasionally losing a record is very low and is barely more than proportional to the probability of loss of a given record.

So I don't get it. If I were running an operation like this, I would prefer not to have a fully immutable ledger full of personally identifiable location, usage, and transactional data.