[nvy]

>I realize that it's more a combination of tradition and their self imposed exile from the world for a long time.

Surely it's more to do with population density? It's not like every Japanese person has one of these combs.

It's much more likely that these niche businesses can exist where population is highly concentrated.

[chrisco255]

Maybe? Even where population isn't highly concentrated, niche businesses can exist via mail order or ecommerce (to gain access to global audience).