I use taxis all the time in South Korea. They are a very viable alternative to car ownership as they are very plentiful and cheap. I am not sure how far it is but the first 5-10 minutes on the taxi cost only $2.00 (2,400 won) and goes up about $0.15 every mile or so after that. I can get all the way across Seoul for under $10.

I would suspect that they are even cheaper in China. Though I think they will be getting more and more expensive over the coming years and as traffic gets worse and worse.