PX10's weren't built by Toyota, they were built, on commission by Toyota, by a coachworks that makes short runs of limited edition Land Cruiser versions, as well as other Toyota models. All were RHD, the production numbers were very small, and from what I've heard, they didn't sell very well, hence its discontinuation. AFAIK Marv Specter's is the only one in NA and one of the few outside of Japan.
70 series is a world-platform, Toyota makes one vehicle base for the whole world, with market-specific tweaks. It was never designed for the US market, and the vehicle would have to be completely redesigned to match US market specs and regulations. Why doesn't Toyota do that? Because then it would have a wimpified vehicle that wouldn't match the needs/demands of the other 110+ countries where the vehicle is sold. They probably crunched numbers and decided it wasn't worth it, let Jeep have the (relatively insignificant) Wrangler market, Toyota is obliterating the big Three in most other segments anyway.
This has to be one of the most over-discussed topics, shows that we're a bunch of passionate Cruiserheads. But Toyota doesn't cater to us, it caters to the mainstream. At the end of the day, if Toyota brought in a batch of 10,000 LHD HZJ70's into the US and sold them for $35,000, it would take a LONG time to sell them all. In fact, I bet you they couldn't. not in 12 months. Sure, a lot of people here and on several other forums would be queuing up, money in hand, but the mainstream would take on look at the boxy, hard-riding, non-cupholder-having sumbitches and would really wonder what Toyota was thinking....