Hmm, that's not correct. Most radio stations I live near don't appear on any internet radio apps, and that's the same with a lot of places. With but a few exceptions, only densely populated areas are fully covered, and that makes up a fraction of the population (our city of 200K isn't).
Moreover, don't listen to anyone who has posted about the iphone's hardware capability, as they are all 100% wrong. The iPhone definitively Does contain all the necessary hardware for FM radio reception. All needed circuitry is onboard the broadcom chip, and it (like on many other phones) is designed to use the headphones cord as an antenna.
As for why the iPhone cant use fm radio, the simple fact is that (like so many other things) Apple (/ Steve Jobs) just doesn't want you to have it. Sometimes it's because they're waiting to perfect Their way (which was reported complete around February this year by an inside source), but mostly it's because they know they can make more money by selling people unendowed crap and later announcing it as a "new feature" (ie lying thru their teeth). Remember the release of video recording? Every iPhone since the first has been able to do it (and a Jailbroken app called Cycorder was created that lets you) but Apple didn't want you to (bc they knew they would be able to capitalize on the announcement later, as they did) so they disabled it.
There is a small effort in the jailbreaking community to find a way around this (see the relevant "thriPhonewiki" pages), but it is currently stalled by lack of technical details on the hardware UART control commands for the broadcom chip. The truth is apple may never "release" (literally, as in out of prison) FM radio capability, at least not until the jailbreaking community has one, and there isn't much reason to expect it (unless of course you're banking on it's successful hacking). My advice to you if you really want fm radio from your phone is to get an android, as they've had fm capability for years (and the 2.3/3.0 update is supposed to be all UI enhancements, so it may even look as great as the iPhone ui soon!).
I hope that properly answered your question.