"ballistic protection around substations"? Are you sure of the costs?
One, the height of a bus bar is required to be at least 8.5 feet above ground, which would require a fence of at least that height. Not the typical 8 foot chain link.
Another, is most substations are not located in the best spots, and many are lower that the ground around them, which would require an even bigger fence.
If you want to see substations with 20 foot concreate/block fence, just book a trip to Peru.
And what do you do about the gates? Air circulation for transformer cooling?
Also, many substations are in rural areas that don't have much in the way of problems.