much more than amateurs "down there"
"Existing PLN equipment operates between 2MHz and 30MHz - right at the bottom of the dial. The only things down there are the amateurs, who've been complaining for a while now, and a few vertical users who don't operate near the homes where PNL is being deployed"
And long-distance over-ocean aircraft, international broadcasters, many federal agencies, the military, shore-to-ship comms, etc.-- PLN affects it all. Having much higher frequencies involved is a mixed bag; using them and dropping the under 30MHz spectrum would keep intact the world-wide nature of the shortwave; but higher frequencies would radiate better out of the power line wires. A better approach is to drop the whole thing and stick to technologies that don't radiate outside of prescribed frequencies.