The point is, only N.America got the 2UZ from the start. Ditto w/ the 4L V6 in the 4runner. That engine didn't migrate over to overseas Prados until a couple years into the new body style. It's evident Toyota is using the US market (where people buy on HP numbers) to test new engines before committing them to overseas markets, where reliability is more important.
That is not accurate. The 4.0L 1GR-FE was introduced on the Land Cruiser Prado in 2003; the same year it was introduced in the US. In fact, I think the Prado120 was introduced before the 4Runner in 2003 so Europe might have gotten the 4.0 a few months earlier.
The real reason the 5.7L might not be on the Japanese version is because it would be an imported powerplant and/or other manufacturing/assembly/regulation reasons. If/when they make the 5.7 in JPN, they may offer it there. Just another possible explaination...