I know a thing or two about rf, emf and electricity in general and I don’t see why or how these hv wires would cause cancer, or if they did why would it be specifically leukaemia.
I’m fully aware though that before we knew about nuclear radiation people would have had similar thoughts about some random rare earth metal causing cancer if you’re not even touching it. So point is, I’ll wait for the proof before I’m convinced, or attempt to convince others.
I’ve also anecdotally noticed that people are concerned about many things where there is like very marginal evidence that maybe this is slightly bad for you but then regularly engage in very well known risky behaviour like eating big macs or driving cars. I might be speaking from personal experience.