I challenge you, or any of the others in this thread who keep throwing the platitudes around, to present some solid reasons of how the knowledge of when technologies were (or weren't) adopted in the past, or when rules or regulations were passed can be put to use today, in 2014 and into 2015 to turn around AM radio's death spiral? What actions can be taken to change the path that AM radio is on that are based on that specific knowledge of the past in this specific situation. I'm not asking for generalities. I'm asking the know-it-alls who keep pontificating about Santayana's famous quote to show how to apply that general statement to specific action that will generate a specific result in this specific situation. If you understand "how it got there", show how that knowledge can be used to take it somewhere other than where it's going.
This has been answered many times, largely by David, but since you ask the question you either ignored the answers or dismissed them as either being less "specific" than you would like or not fitting your own concept of reality. So I will summarize, with apologies in advance if this is too much a list of "generalities" for you to accept.
1. AM is subject to electrical interference. Always has been, and much of that is the fact that the band used for AM radio transmission falls within those frequencies which are the most prone to electrical interference. Household appliances interfere with AM reception. Being too close to high-voltage transmission lines interferes. So do fluorescent and LED light bulbs. And the list of such interference goes on (but I've made the point). FM is not subject to this interference, and listeners know that. So unless they have no other choice, they will choose FM over AM.
2. The decision to implement IBOC on AM creates sideband emissions to adjacent frequency stations hundreds of miles away, thanks to the way AM signals propagate. If you have ever heard IBOC "hash" drowning out the station you are trying to listen to, you already know why it will make listeners stop trying to listen to that station. And they'll likely go to FM and never come back, no matter how compelling the programming.
3. Ah, programming. If you are going to try to overcome the limitations, you have to create programming that will attract listeners who will put up with all the interference. That's why ethnic and religious formats work well on AM: In nearly all cases, that interference-riddled AM is the only place those listeners can get what they want. They are a captive audience, unlike the more typical listener that will trade off programming to get something close to what they want on FM.
4. The failure to adopt regulations to better protect AM as interference sources multiplied is a failure that goes back way too far to undo. The approval of IBOC, even in the face of engineers' warnings of sideband "splatter", is another failure. So was the AM stereo standard debacle.
5. Urban sprawl. Even those AMs who had great city-wide coverage as recently as the 1960s and 1970s have found that the listenable signal didn't grow as cities developed further outward. (Duh, right?) But the interference sources also grew with the urbanization, having the effect of actually
shrinking the usable signal area.
Your final request (or is it a demand?) is where your thought process errs.
If you understand "how it got there", show how that knowledge can be used to take it somewhere other than where it's going. You tell me: How do we "undo" any of the above five reasons that AM got to where it was? I can't rewrite the laws of physics ... can you?