Burying those lines is not practical. Inspecting and repairing them is. The problem is significant deferred maintenance. Buried lines cost much more to maintain, in addition to installation costs even where they are feasible. It's better to make sure (1) the towers don't fall down (2) into a forest ready to ignite. That can be done, but we have to pay.

If Workers & Resources: Soviet Republic taught me anything it's that underground power lines are for the capitalist bourgeoisie.

This is a classic prisoner’s dilemma, and you’re advocating for both sides to hit “betray”.

Perhaps if enough drones did this, they would indeed bury the lines. But that would be strictly worse than a world in which they didn’t bury them, and drones don’t steal electricity regardless.