You are wrong, at least in WA State. We don't have emissions inspections anymore. The VAST majority of cars on the road in our state, today, are computer controlled FI, with catalytics. So it's a waste of money and time to test cars that rarely fail the test.
I suppose a lot of the more densely populated urban areas are generally more liberal, so more likely democratic. And urban areas often have air quality problems from cars and industry. But I think it's a far leap to conclude that only Democratic controlled areas pursue emissions testing.