There are a few related risks coming into play here, and controlled burns specifically along power transmission paths may not be appropriate.

Fire risk largely boils down to:

1. Ignition.

2. Fuel.

3. Weather.

4. Endangered resources, particularly but not exclusively structures.

5. Fire spread mechanisms.

Weather is largely beyond control, but includes both immediate (high winds, low humidities, high temps, dry soil and vegetation) and long-term (drought, flood-drought cycles) elements.

Ignition is where PG&E are largely concerned. Electric lines and other equipment can and have caused previous fires. Keep in mind that activities such as mowing grass, getting flat tyres, and hammering have caused previous major conflagrations. At this point, ignition is all but a certainty.

Fuel includes both plants and structures. Due to 80+ years of near-total wildfire suppression, and exacerbated by climate change and plant disease, fuel loads are extreme.

Wildfires are typically wind and ember driven, rather than simply being a wall of frame. Hotspots and ignition points occur outside the principle fire front by distances of hundreds to thousands of metres -- a quarter mile to several miles in Freedom Units.

Structures specifically are vulnerable to wildfire largely when embers impinge on structures or immediately surrounding flammables: exposed decks, surrounding brush, eves, and the like. If immediate ignition can be limited, through architictureal, landscaping, or treatment (sprinkler, foam, gel) mitigations, most structures are actually fairly resilient, though heat and smoke damage can still result. A near wall-of-flame approach can still shatter window glass and ignite interiors through radiant heat.

To your suggestion:

What safes transmission lines more than anything is clearing any nearby brush or trees. You don't need to burn it away, you simply need plant matter not to contact transmission wires and equipment. This is generally an easier, and far more controllable approach than even prescribed burns. Road and heliocopter-based tree-trimming and removal can and do work.

Prescribed burns can work on overall fuel load. This is a treatment applied generally at a regional level, affecting acres to miles of terrain. It's generally best done during or immediately after the wet season (to avoid uncontrolled burns), and away from structures, including power equipment.

One of the huge weaknesses of many utility systems is adequate monitoring. For all the industry advocacy I've seen of "smart meters" and the like, applying sensors, monitors, and active monitoring of transmission lines, gas likes, water systems, pipelines, etc., seems absolutely primative. Smart meters are revenue-generating (or loss-avoiding), equipment monitoring and controls apparently aren't seen that way.

Finally: construction and emergency planning around wildfire events clearly needs to be upgraded. The good thing about institutional and methodical approaches is that they can incorporate collective wisdom. The bad thing is that they are frequently reactive, conservative, and cruft-ridden. Early-stage approaches are often grossly inadequate, late-stage approaches are often geared at outdated assumptions, experience, and methods.

Paradise, CA, had a wildfire disaster plan. It was abolsolutely inadequate to the situation faced. The 2018 Camp Fire began at 6:33 am. First units were on scene slightly before 7 am. As of 7:34, 911 operators were still telling Paradise residents there was no immediate danger. (https://ktla.com/2019/02/01/first-camp-fire-911-calls-reveal...). The fire entered Paradise at 8 am, some 20k (16 miles) from the ignition point, and evacuation was not ordered until about 10 minutes later, and then for only sections of the town, as the fire response plan called for staged evacuations from specific zones. Residents died in their homes awaiting specific evacuation orders which either never came, were transmitted over inadequate channels, or were never received.

Video interview / docu covering many of these points: https://youtube.com/watch?v=gxt7L4x_NQo

As with other megadisasters, a huge contributing failing was of imagination and understanding by planners, authorities, responders, and residents, both in the moment and for years beforehand.

https://en.wikipedia.org/wiki/Camp_Fire_(2018_Wildfire)

PG&E were directly responsible for part of the risks, and were absolutely negligent in this and other recent disasters such as the 2017 Northern California wildfires and 2010 San Bruno gas pipeline explosion. Though the ultimate fire was all but certainly inevitable.

I happened to travel along the next W-E highway north of Paradise in 2015, taking CA-32 and CA-36 from Chico, CA, to Mt. Lassen, in early October. I was struck by how bone-dry the forest was, as well as the temperatures (~90F) and humidity (low). Thankfully winds were nonexistent. But as someone who's spent a fair bit of time driving through remote, mountainous, and forested terrain, I felt distinctly uneasy and could directly perceive the risks. I was happy to be through the region, despite its beauty (and it really is a fantastic drive).

(I've done a number of rural-country road trips since 2000, and the memories of both fire scars and regions later consumed by major fires has left a strong impression.)

News of the Camp Fire three years later did not surprise me. The friend I'd visited in Chico was my first source of news of the fire via social media posts.

There are numerous videos of the Camp (and other) wildfires on YouTube. This is a well-produced synoptic overview by Vox which does a fair job of conveying the scope, scale, speed, and effects. Nothing but seeing in person can truly do the phenomenon justice.

https://youtube.com/watch?v=nwup6tA_OzQ