For example if you multiply the USD rate of 1 BTC with the CNY rate, its 1 BTC = CNY 73,600, but exchanges there have it around CNY 75,500.
In other countries in Asia and South America also BTC is more expensive to buy in non-USD currencies than in USD.
Why is this the case?
Maybe you are getting this wrongly. The price of bitcoin differs from one exchange to another, and also fluctuating. Maybe the difference is what that is confusing you.