I didn't claim cross-dc consistency. I said failover, which is shockingly hard to make many competitors do. The key here is that only one DC can take writes but the failover works transparently with your client (also with clear SLAs).
An interesting thing to point out is the current beta for Cloud Spanner does not have multi-region deployments... and instead, allows you to do single-region deployment in your choice of 3 (not >30) regions:
