I would certainly assume there are regulatory limitations, but there may be some scope to get around them. Uber uses different models in different cities in the U.S. For example in NYC, they don't charge commission on taxi dispatches...basically a bone they had to give the taxi drivers to get them to drop their opposition to Uber. In NYC, Uber makes all their money off private livery vehicles.

I think the issue in Japan is primarily whether taxi and hire companies have any flexibility to adjust rates. I don't know what the current regs are. If I were Uber, I would try to target some of the smaller hire companies or I would be looking at locations other than central Tokyo where taxi service is not so good and not so ubiquitous