Taxi comes from French, which took it from German, from Latin. Words travel around. When a language takes a word from another it is a 'loan word'. I see people of many languages using 'hello' to answer their mobile phone. Words have a life of their own and people pick up on them for different reasons. 'Ciao' has moved from Italian to various languages. This is often for convenience, but can be because we like the sound of them, etc.