I think it's a failure to solve 1 + x = 2. x is the percentage of the power grid controlled by this system, which has risen over time.
So at design time, the threat is just that people can turn off street lamps, which you can do with a BB gun. Then you expand to home solar. Also not so interesting.
But then you expand to be a significant fraction of the grid supply and load. Now there is a substantial target that actually needs security, but which requires a full redesign.
So at design time, the threat is just that people can turn off street lamps, which you can do with a BB gun. Then you expand to home solar. Also not so interesting.
But then you expand to be a significant fraction of the grid supply and load. Now there is a substantial target that actually needs security, but which requires a full redesign.