It's not a tragedy of the commons because generators will have interest in seeing the network continue to function.
Just like the herders have an interest in having the common pasture continue to grow grass?
No, there will be instititutions with a high value to protect. Costs of protection are a 'tax' of sorts, but they are unavoidable. They are not a tragedy of the commons scenario, each is still looking out for his own interests, and his interests
benefit others. It's a postitive externality.