Though not spoken about online very much, I am guessing Nissan also has battery constraints on the number of bigger batteries is can sell, (Like Kia/Hyundai) but has better production capabilities for the 40kWh battery across multiple sites. This is reflected in the deeper discounts for the Leaf over the Leaf Plus and why the 40 is the only model available in many markets (Australia, Philippines, Indonesia, South Africa, LATAM, etc.). Its only selling the 62 in Europe, UK, US, Japan, and Canada I think due to competitive pressures in those markets, and in many of the markets only a top trim level to help manage demand.
Certainly even part of Teslas strategy in dropping the kWh badge on the cars is so that as they develop efficiencies, they can reduce the battery footprint on the same car while offering an equivalent EPA.
2019 SV Plus Silver 6/19 purchase 7,000 Miles
2013 Leaf SV
100 Mile Club Member (Number 87)
Max distance on 13 Leaf: 120 miles
Max distance on 19 Leaf: 242 Highway 4.5 miles/kWh