There are just very few schools on the island and not everyone can go to study chinese.
During the japanese invasion, the island was declaired as an ethnological research area, and closed the access to the pubblic. This prohibition lasted until the 1967, despite Japan being driven out by the new government of the Repubblic of China in 1945.
For this reason the Tao people among all the others aboriginals ethnicities have been able to preserve their original traditions and beliefs of Taiwan.