Two factors: sprawl, NH is very sparsely populated, this calls for a lot of lines at risk from trees and it also costs more for the state to operate so inherently lines are in rougher conditions. Mixed use medium density zoning which we see in a lot of other states or Canada has very reliable infrastructure and tax income to upkeep ratios for the city.

Other factor is climate, we are in the sweet spot for snow rain freeze-thaws, this puts ice and weight on trees and lines. Go north more and it's just snow, go south it's just rain.