The measure, called Question 3, prompted heated debate in the months leading up to the election. Central Maine Power and Versant Power, the state’s dominant utilities, poured more than $40 million into a campaign opposing the referendum, outspending Pine Tree Power advocates 34 to 1. Political groups funded by the utilities and their parent companies mailed flyers and aired ads on TV, radio, and social media, urging Mainers to reject the measure, which would have effectively put the two companies out of business.
It's part of it, but it was this cheap even before those deals were made. Of course geography has a lot to do with it too!
Regions who have a good source of hydro power usually the most flexibility to change up systems relating to electricity.
Its why for example Norway is capable to flip to EVs so quickly (in 2022, 80%+ vehicles sold were EVs). 95% of Norway's electricity is hydro power.