Why burying power lines for wildfire prevention is effective but so costly

Burying power lines is an expensive but sure-fire way to practically eliminate the risk of utility-caused wildfires, which have devastated towns across California. PG&E, the nation's largest utility, has been found liable for numerous wildfires in the state, and has a plan to underground 10,000 miles of distribution lines in fire-prone areas. But this plan would cost tens of billions of dollars and would be paid for by customers, causing some to advocate for cheaper, alternate options.