I grew up riding in Maine and in certain areas the trails would follow the power lines for miles. Back then we mostly rode atv/snowmobile trails and they followed the power lines because they were direct and easy. I’m not sure who owned the land but I never had an issue. The trails were usually rocky, ledges, mud pits, your typical Maine trails… Where I currently live I wouldn’t bother trying to ride the power lines. There are much better riding options.
I’m sure it really depends where you live. It could be a fun adventure or it could be overgrown madness