That's a blessing and a curse though for interactive applications. One FM transmitter can easily cover millions of people - and 20MHz of spectrum isn't very exciting spread over that many people in my eyes.
So the way to use it more effectively is to build more transmitter stations at a lower power, but at that point you're competing with cellular networks which have access to probably 10x the spectrum and already have a load of infra built out to support that.
For example, if you used FM for LTE/NR it would be completely congested 100% with even just signalling overhead of the time apart from very rural areas (as suddenly everyone's phone that has no service because of being out of the reach of any mast suddenly gets it - perhaps because of thick walls etc).
Similar if it was used for WiFi - the transmit power would have to be so low to avoid interference it would have no benefit over current spectrum (2.4GHz doesn't work in most places for this reason).
And rural areas already have starlink - which has 2GHz of downlink frequency alone (plus they can add more somewhat easily, which is impossible for FM).
So the way to use it more effectively is to build more transmitter stations at a lower power, but at that point you're competing with cellular networks which have access to probably 10x the spectrum and already have a load of infra built out to support that.
For example, if you used FM for LTE/NR it would be completely congested 100% with even just signalling overhead of the time apart from very rural areas (as suddenly everyone's phone that has no service because of being out of the reach of any mast suddenly gets it - perhaps because of thick walls etc).
Similar if it was used for WiFi - the transmit power would have to be so low to avoid interference it would have no benefit over current spectrum (2.4GHz doesn't work in most places for this reason).
And rural areas already have starlink - which has 2GHz of downlink frequency alone (plus they can add more somewhat easily, which is impossible for FM).