You don't seem to realize that most cars are uninteresting and worthless. The agencies purposefully put in the costs so that they get rightfully junked. Specialty cars, our cars, do not.
IF they did not, older cars would become paradoxically more valuable and undermine the mission of pollution controls.
A cali-spec 1970 Mustang definitely has PCV and evap, and probably has an AIR system (smog pump) as well. Passing the visual inspection at least means that it (probably) won't cause photochemical smog in LA because of blow by and tank venting to atmosphere, which is most of its emissions burden as long as it's in half-decent tune.
And yes, it's all about driving the cost of non-compliance with standard up enough that it's easier to either junk the car or make it compliant than to operate non-compliant. The other thing California is all about is passing an inspection test, because eyeball time is cheaper than dyno time.
Most other states don't care as much, especially when the car crosses the mystical 25 year age boundary. At that point, they know the car is either at the very tail end of usability or is being actively maintained and is probably in better shape than most 15 year old cars on the road. They generally require a visual check, an OBDII no flags and OK check, or an idle sniffer test on OBD1 and earlier.
When I was in an I/M county in PA, the requirement was that the pre-OBD2 car pass a 2000 RPM no load sniffer test. One year - around 2006 I think, my ratty '93 Celica (now parts car) failed (high CO, HC and not much of a working cat). The solution I was offered by the shop was to buy an intake system cleaning service (a BG cleaner sprayed into the throttle body) which, (what a shock) was just expensive enough to trip the 'you spent enough money trying to be compliant, so you can have the 'I tried and failed' sticker flag'.
I'm a former vehicle emissions scientist and pretty good mechanic. It would be kind of embarrassing if I couldn't get the (mechanically decent, if well worn) car to pass a no-load sniffer test. Besides, it was mostly stock, so likely not a lot of work.
I declined the offer, took it home, changed the oil, checked the PCV system (was fine), retarded the ignition timing 5 deg (2 deg ATDC), and brought it back on Monday. It passed easily. I went home, advanced the timing back to 3 deg BTDC (spec is TDC), which I found to be the best power sweet spot on that car, and drove it for another year.
Honestly, if your pre OBD car is unmodified and doesn't burn huge amounts of oil, it's not that hard to get it to pass a sniffer or even an I/M 250. You just have to know how to do it. I chalk it up to consumer culture and a lack of scholarly skills.