FM radio bands are in fact used for various emergency services, but they are more specialized in usage https://strykerradios.com/ham-radios/ham-radio-emergency-fre...

AM radio travels farther for the same energy consumption, as a feature of the lower frequencies used. That means they can provide emergency information to a much larger area for a given power supply. AM radio also doesn't rely on huge towers since the waves can bounce off the ionosphere and travel as ground waves.

AM radio receivers are also very simple to make--check out the crystal radio!