See sibling note by 'rayiner. FM as broadcast now is really old tech. Car radios would have to be updated to have cognitive radio capability, if this regulatory regime were extended to that band. But that doesn't have to happen soon; the spectrum is vast and could certainly accommodate more unlicensed use without inconveniencing this particular use.

EDIT: In case this is still unclear: I'm talking about opening specific, limited bands of spectrum to unlicensed use. I would not nominate FM radio as the first such band. Just as wifi chips today are capable of not interfering on bands they don't use, super-wifi transmitters would not interfere on bands they don't use.