Also way easier in countries where you don't speak the native language, and mitigates the risk of card skimming if paying by card.
Well not sure about card skimming avoidance & taxis...
A friend of mine had her card skimmed by a taxi taken from Sydney Airport to home. A pre-paid $2,000 debit card.
It was brand new (present from parents) and she'd had it as an emergency when on holidays, so decided to use it now back home. Two days later went to use it again - failed, tried again & failed. Went to the issuing bank & told it had zero balance. Other than the first trip it was all used up on taxi fares in MELBOURNE the next day.
So she went to the police and was told 'What proof do you have that the taxi driver was involved?'
Transactions!
Police - 'Circumstantial, a clever lawyer would just argue it was a coincidence, and as the transactions were in another state then we would not be able to investigate ourselves.
Happens all the time.'
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Moral of the story:
NEVER sit in the front passenger seat in a taxi etc. Sit behind the driver's seat when paying using the mobile terminal
If in the front passenger seat then the taxi driver hands you the mobile terminal which you hold with one hand, and you enter the PIN with your other hand = nothing to hide your PIN from the taxi driver's gaze.