I'll only say this once:
Radio has its place, and so do smartphones (or phones in general), but each has its weaknesses, and one must be aware of them and prepare accordingly.
And human error plays a role in what would otherwise be a sound system, too.
In all the California wildfires, a recurring theme was that the emergency alert systems were not activated for one reason or another, even in situations where the equipment was in good working order and there would've been ample time for people to act on the information. For example, the evacuation sirens could've been activated during the fires in Lahaina, but they weren't. This was due to an error in judgement, not equipment failure, so would activating those sirens have been meaningfully helpful? It's hard to say, but the point is, the systems themselves aren't always the problem.
In other words, even the best, most comprehensive emergency alert systems in existence are only as strong as their weakest link, which is usually the humans who maintain and control it, not generally their susceptibility to damage or destruction (assuming they're designed to resist damage).
Sometimes an otherwise decent system will collapse when there's a high demand (in the case of the 1989 earthquake, that would be early analog 1G cell networks and copper landlines, both of which had a finite capacity), but again, there's nothing inherently wrong with the system; it simply was not designed with the needed capacity, which, again, falls to the human designers who failed to take that need into account.
Radio (AM, FM, or otherwise) as a means of broadcasting emergency alerts and info is fine and good, but yet again, it's only as good as the humans who operate it, and, as has been pointed out countless times in countless posts, because of the budgets of many stations are being cut and staff are being reduced (and in some cases, eliminated altogether) and the heavier reliance on shared resources and automation, any advantage radio has of actually being a good source of info during an emergency has been severely undermined. For example, when there's a disaster or emergency, a fair number of stations (particularly smaller ones) will just carry on with their normal, pre-programmed, automated schedule, seemingly oblivious to said disaster or emergency, even if they happen within their local coverage areas. How is that going to help anyone? If you're lucky, the EAS alert will sound, but don't expect anything else from a 100% automated station.
Smartphones, imperfect though they may be, do help to fill this void, so in a way, we're probably better off now than at any other point in history as far as getting quick and relevant info during emergencies goes, since we no longer have to rely on a radio station that may or may not broadcast any. At least in theory.
In practice, however, the chances of getting any info at all – from any source – are 50/50 at best.
c