Part of Japan's emmission program is to replace the entire engine every 30,000mi or so.
Consider what kind of miles these would be with so little open road.
If you knew you had to replace your engine at 30K, how often would you change your oil?
Also consider with so many people and cars navagating such narrow roads, it is not uncommon at all that new cars are envolved in accidents almost as fast as they are sold.
I have never heard someone complain about a JDM engine. I can recall at least two brand new American replacement engines that had problems.