Logistics and attendant expenses most likely - especially with practice to gain any actual benefits.
Say everyone has a registered nonrepudiatable cryotographic certificate - a decent idea in theory. However apply it to every accessible grid communication part including ones which may cycle in and out and could have secrets extracted. Suddenly it doesn't provide as much benefit if a hacked SmartMeter can get in anyway and there is deniability. Better than nothing but you could have likely gotten better bang for your buck with strict firewall rules or hiring a swarm of consultants.
Similarly vetting commands has two problems - one is that reaction time may be critical. Second the judgements themselves are complexity and may be a source for errors - especially when they are "triage" ones that cause a shutdown or damage to avoid greater damage
Say everyone has a registered nonrepudiatable cryotographic certificate - a decent idea in theory. However apply it to every accessible grid communication part including ones which may cycle in and out and could have secrets extracted. Suddenly it doesn't provide as much benefit if a hacked SmartMeter can get in anyway and there is deniability. Better than nothing but you could have likely gotten better bang for your buck with strict firewall rules or hiring a swarm of consultants.
Similarly vetting commands has two problems - one is that reaction time may be critical. Second the judgements themselves are complexity and may be a source for errors - especially when they are "triage" ones that cause a shutdown or damage to avoid greater damage