Its not unique to the photographic film industry, to offer products optimised or branded differently by market. There are plenty of products by US manufacturers for example that are only sold in the US/NA market even when they are global companies. Global 'cars' are still a relatively recent idea and the same platform is often badged or styled slightly differently, sometimes for standards reasons, but mainly due to consumer preference or market price placing.
In Fujis case reasons may include;
- Optimised products for the home market, for example around colour or skin tone preferences/fashion, e.g. western european preference for skin to look tanned vs neutral/paler skin tones in Japan/SE Asia. Superia premium is claimed to be optimised this way.
- Stronger light makes 100 the default colour film rather than 200 for Europe
- Ability to sell similar or marginally different products at different price points, e.g. Superia Xtra 400 vs Superia premium. Latter sells for >30% more in Japan (when they offered both there) but probably doesnt cost 30% more to make
- Reduce costs by limiting SKUs for export so why offer both 100 and 200 to global market if sales will be the same
- Related to the above, there seems to be fairly high import tax for film into Japan (historically kodak was alot more expensive than fuji), so fuji is able to make higher profits there plus lower cost of distribution.
Kodak have also done the same in the past, for example Colorplus was europe only and Pro image only sold to SE Asia/Latin America. Ilford with their Pan 100/400 film and Kentmere was originally a US market product.