First off, all types of generalisations are bad :-) So, I argue that in some cases, government regulation is good thing, within bounds, reason, etc, etc.

Where there is a _shared_ resource, it is usually a good idea to defer regulation thereof to a third party to govern access (the Government) which in an ideal world is appointed by, and acts int the best interest of, the collective owners of the resource.

In the Real World, this third party (or their agents) are usually in the pockets of whoever has money, but that's a technicality.

Now, in the case of spectrum, let's compare the US and Canada to The Rest Of The World. One has GSM, the other has CDMA, GSM, and probably still some TDMA here and there. In one, users can generally freely buy whatever device they like as long as it conforms to the Government standard, in the other, you have to use whatever your carrier chooses you can have. Yes, you can freely choose carriers, but this is also the case in the more developed parts of The Rest.

Cars are generally not a shared resource (though the air we breathe and the roads we drive on are) so the argument is less relevant for regulation. If taxation for things that affect the shared resource are increased, the market will encourage individuals to choose differently. If individuals can save on taxes by choosing a lower emission vehicle, the market should find the most efficient way to provide this to consumers - and is not constrained to any particular technology choice by decree. Bring on the plug-ins and high-efficiency diesels!