Maybe that is so in the US. In Europe, "Smart Grid" technology embodies the whole thing i.e. right the way up to transmission level.
Power systems are highly interconnected and operate in real-time. There's relatively little economic benefit in just making the last mile "smart". The big wins come when the whole supply chain is smart, enabling real-time pricing, despatch, outage management, etc.
Even if this technology starts out by being deployed at the last mile, it *will* end up influencing and/or controlling the higher level distribution and transmission systems. So it's important to get the security right at this stage. Otherwise we'll end up with millions of insecure nodes out there and no way to actually gain any genuine benefits from the technology.