Probably because unlike the UK those markets still have huge subsidies for buying ev's. Also the US Leaf can get the massive tax credit because US leafs are domestically built thus eligible.
With no ev grant in the UK anymore sales dried up on the e+ because its only a few grand cheaper than the far better built/upmarket Japanese built Ariya with better performance and standard features. People on a limited budget who could afford the 62kwh leaf with the government ev grant would just settle for a pcp on a Leaf 40 instead and people with bigger budgets would skip a loaded 62kwh leaf Tekna anyway and just go for the the Ariya.
This is probably the reason why Nissan recently introduced a cheaper Ariya ENGAGE spec for £39,645(£36k after discounting) after discontinuing the bigger battery Leaf's to make it easier to upsell to potential buyers.
The biggest problem Nissan currently has in 2023 is not updating the leaf which is basically the same car as the funky pokemon looking model introduced in 2010 which is in turn based off a beefed up 2004
1st gen Nissan Tilda .. Now the brand has a huge gulf in its ev range with the ground up all new premium Ariya and the budget and aging Leaf 40 with its legacy holdovers like soon to be extinct CHAdeMO rapid charging connector..
To further add with the influx of 'product dumped' ccp owned chinese evs such as the SAIC MG4 and ZS EV flooding the lower end market with cheap subsidized low deposit 0% pcp deals further takes sales away from the Leaf.
The main point is that Nissan wasted its huge head start in the ev field and should've introduced the 3rd generation Nissan Leaf hatchback around the time the Ariya was launched, yes Nissan delaying and pausing development was partly done to reverse the destruction caused by their criminal fugitive ex ceo carlos ghosn but its a great shame the company allowed the Leaf to be neglected in the range, the Leaf is still great value for money but that isn't enough of a selling point with the huge amount of new evs being released.