Well, my LUV didn't come with any of it's original smog parts, so hopefully I'm off the hook, the DMV registered it that way.
I just laugh because I have to take my '82 fullsize in every damn year for a smog check, it's 8601 lb GVW which is classified as heavy duty. All this means is no EGR and no catalytic coverter. I still have A.I.R., PCV, thermostatic air cleaner, etc. The guy tells me, and I have the sheets to prove it, that it runs really clean, and is even cleaner than some of the new Hummers and Suburbans. Below average on HCs, NOx, and CO2. I was reading about PCV, that takes care of a majority of HCs which form smog, and A.I.R. helps too. If your car is in perfect (or at least really good) tune, which many especially street rodders make sure of, you don't need a lot of the smog stuff to get a clean tailpipe reading.
The thing is, the number of hobbyists with no smog equipment is minuscule compared with the number of piece of crap Toyota Camrys, Ford Aerostar Vans, Chevy Astro/GMC Safari vans, and other 80s wonders that are in Los Angeles. They do need pollution controls, and I don't think they're a bad idea. My father-in-law went to college here in Pasadena in the late 70s and he said they never saw the mountains until one day in Winter each year, and that his lungs would be burning after a football game. Smog is not good and I think if there are prudent things you can do to prevent it, such as make sure your daily driver is in good working order, then weekend cars should be fairly unregulated because they contribute basically nothing to the pollution problem, especially in places with a lot of trees (basically anywhere but LA).
Next in line please come up to the soap box.