- Holding a regular driving license for n years
- First aid training
- Taxi specific theory/practical driving test
- Passing extra vehicle tests (I know where I'm from they used to require taxis to be fitted with small fire extinguishers for example).
- Background check
"It has been called the hardest test, of any kind, in the world. Its rigors have been likened to those required to earn a degree in law or medicine. It is without question a unique intellectual, psychological and physical ordeal, demanding unnumbered thousands of hours of immersive study, as would-be cabbies undertake the task of committing to memory the entirety of London, and demonstrating that mastery through a progressively more difficult sequence of oral examinations — a process which, on average, takes four years to complete, and for some, much longer than that."