I think authority is a critical differentiator between the SRE described in the Google book and SRE as it’s practiced elsewhere. Google SREs can impose moratoriums on feature development or deployments if they judge that a product is becoming critically unreliable (which has a well-defined meaning based on SLO breaches). SRE teams will also sometimes “offboard” a product that is insufficiently respectful of the finite attention that an SRE team needs to spread across multiple products, returning full production control to the development team along with the pager and all responsibilities thereof.