There's another factor in the acceleration of the AM dial in the Bay Area, the adoption of technology that creates or exacerbates the noise floor on the AM band. There are a lot of technically adept folks who live here, and who solve problems by being early adopters of technological solutions. Problem: ridiculously high PG&E electric rates that would make my friends blush at Con Edison/NYC. Solution: LED's replacing tungsten or halogen everywhere. Problem: two-income couples who needed to each have their own secure network while working from home during and after the pandemic, plus segregated capacity for the kids stuck at home. Solution: multiple personally-owned routers that are subnetted behind a utility co.'s (Comcast, AT&T, Sonic, etc.) own equipment, doubling, tripling or even quadrupling the RFI being generated.
Having multiple routers shouldn't be necessary for home use. We never needed more than one when working from home, and there were two of us, working at separate companies, able to use Zoom, Teams (yuck), etc. simultaneously with no problem as long as IPsec passthrough was enabled on the router. Encryption was then end-to-end at the network layer. Effectively, each user had a VPN (as long as split tunneling was not allowed, which it usually isn't) managed by our employers. We did have a booster upstairs since the main equipment was downstairs in a corner, but it functioned transparently to the downstairs network. If there was ever a problem, it was with Comcast, which never seemed to realize that the daytime is not a good time to push changes to production. If we had stayed in Oakland, I would have gotten fiber with AT&T. Same deal in Denver, except we're not working, but still on computers a lot, and we have fiber. But we have something like 20-25 devices on the network on at all times for various purposes, almost all on Wi-Fi. They all coexist peacefully. The main radio noise producer is the network termination device that's in a downstairs closet. It will destroy AM reception within about 6 feet but that zone of noise falls off very rapidly. Oddly, the best place for AM reception in the house is just above that closet upstairs. At that point it's far enough away from the NTD to avoid being a problem.
As far as I'm concerned, the noisiest piece of technology out there is the dimmer switch. I've tried to keep them out of this house, though I may have to relent in one instance due to plans to replace an ugly light fixture. I'm hoping we can get a dimmer switch that's electrically quiet.
So some of the folks in San Francisco work in high tech. Most don't. More, just like those in Mobile and Wichita, work in insurance offices, real estate agencies, the back office at the supermarket, the local branch of a brokerage house and the like.
Rural electric cooperatives in many areas are putting in fiber. Farmers tend to be heavy users of technology, and have been for years, so the demand is there. The situation is still far from ideal in some areas, but improvement has been steady. Small towns also view quality Internet connectivity as a competitive advantage in attracting business and residents. As an example, my mother's hometown of 6,000 people in a somewhat isolated part of Missouri now has fiber available anywhere in town and along more and more routes in the surrounding area.
Yes, there was a big gulf in connectivity between the Bay Area and most everywhere else...in 1995. I remember well the hassles in trying to get Internet connectivity in Kansas City. Of course, it was dial-up. Thirty years later, quality connectivity is more evenly distributed, particularly in metro areas, though some rural areas are still left out.