I’m not quite sure what point you’re making here. Spanner ensures causality by waiting until TrueTime tells you that the commit time is considered “in the past”

I’m not quite sure what point you’re making here. Spanner ensures causality by waiting until TrueTime tells you that the commit time is considered “in the past” for all replicas. There’s nothing swept under the rug here and this is a theoretically sound way of ensuring consistency (as long as you’re willing to sacrifice correctness if you’re not able to keep clocks in sync).