It's not the same thing by any stretch of the imagination, from consumer interest and behavior to available technology to the underlying reasons. I'm not sure "apples to oranges" quite applies strongly enough.
No one needs to save AM radio. No one needed to save the horse and buggy industry. Much like buggies became a niche (hi, Amish country), AM has become a place for some niche of its own, be it talk that doesn't yet have a home on FM in a given area, religion, ethnic or whatever. '
We have digital audio distribution. There are near infinite options to get content of your choosing through a plethora of services and apps. Yes, some you need to pay for--welcome to the real world. Some are free, or lower cost, with the "price" being ads. Doesn't matter; the options are there.
You know how "HD Radio" caught on like wildfire with FM? How people were storming the aisles at Best Buy to get the latest receivers for home and car use? How the home stereo rack made a stunning comeback?
Yeah, me either.
FM sounds better than AM, so it supplanted it long ago for most music formats in most areas. What, exactly, would some FCC mandate have accomplished? No one was going out to buy an AM radio because...hey, now it's digital! We moved on. "Radio" is really audio content, and now that's delivered in multiple ways, just like TV now includes all those streaming services. Think like a consumer.