[corint]

What prevents those details from being mapped by volunteers though? Consider openinframap, for most western nations that looks to be pretty spot on?

[bdamm]

Nothing, but some of the details are not available to volunteers. Even if you know where all the lines are, it may not be clear how to attack those lines. There are redundancies and branch switches and feeder cross connections. If you knew where all the switches and cross connections were, though, then you could really take advantage of any weaknesses in coverage.