^^^ Another factor is time. It takes 50% of the time to charge at L2 as L1. While this is not a big deal with the Prius PHEV, it becomes a big deal when you have an EV, where a full charge for a Leaf at L1 would take 12-14 hours. L2 complete charge is still 7 hours. This is likely another reason for the smaller capacity battery in the Prius. Enough to get a tax break, but not enough to need a new infrastructure at home. I like charging at L2 stations - 90 minutes goes by fast if there's something to do. But that time is not worth an extra $1200 to me right now.