You do realize that the only reason the PHEV's you reference exist at all is because of the ZEV credits?
If they don't meet minimum numbers in Section 177 States, they are required to either:
a) Pay a penalty
b) Buy credits from a manufacturer with excess (Tesla doesn't produce ICE vehicles so all their credits are available on the open market)
The end result is it effectively costs them more to sell outside of CARB States, so that is where the inventory tends to go. What would you do if your company was faced with the same choice?
For 2019, minimum ZEV % increased from 4.5% to 7%, and TZEV credits (from PHEV's) are limited to 3%. As you can see below, the ramp continues.
The penalty per missing credit is $5K. A Tesla M3 earns 4 credits, which is equivalent to $20K per car in "penalty value". Tesla sold $103 million in ZEV credits in 2018 (they sold a cumulative $890m from 2013-2017). The "free market" value of credits is softening considerably - in earlier years they were going for the full $5K.
A Clarity PHEV earns 1.2 TZEV credit, a Clarity Electric 1.9 ZEV credits.
A Prius Prime would earn .9 TZEV credits, a 40kWh Leaf 2.9 ZEV credits
This is just a very basic look at the rules. For those seeking more confusion:
https://www.arb.ca.gov/msprog/zevprog/zevtutorial/zev_tutorial_webcast.pdf?_ga=2.135670135.716043205.1564811029-668174325.1564811029