Uber's model of private drivers was not legalized in Japan. Need a taxi licence. Lobbying. Backend pressure against taxi company owners who started to partner with Uber. Go grabs 70% of ridehailing market in Japan, and about 1/3 split between Uber and other rivals. Uber is popular with tourists in Japan, and tourism has recently seen a big influx.
Uber lost out to local players in China and SEAsia also. Skorea had its own app, lobbying so laws only allowed Uber to be used by people with a taxi license. Uber has done well in Latam.