Since you asked, I've worked for an environmental regulatory agency in California for the last 15 yrs. You can probably guess which one. Needless to say, I correspond with my EPA colleagues on emission-related assignments regularly.
That's irrelevant though. As a gearhead in California, I was simply pointing out the blatant misinformation in your post when you said "If your car is 1973 or older, you do not need to add cats to your car except in California." That's absolutely untrue.