If the automakers don't care about reception quality, then why oppose this law? Bad reception in their cars will make their cars look bad, if only by a little, which is why they care.
I can't imagine choosing between two cars and picking one because of its AM radio reception. I wouldn't even make a bet that I know if my car can receive AM.
Between the standard AM radio content and the availability of better options like streamed audio, I just don’t see people caring.
Until and unless an emergency does happen, in which case, they’d have to actively know to tune in (unlikely) and have to not want to pull over to listen.
They’d also have to be in a situation where the other emergency broadcast tools on their phones don’t work.
I just don’t see it being anything that any number of consumers would care about, beyond the standard number of outliers that are usually accounted for.
I think the latter is significantly more likely.