The passenger fumbles with the machine (if you just pullout the card slightly and reinsert the transaction won't go through on most rear fitted machines). They then say, they have no other form of payment.
A couple of times I've managed to beat them at their own game by setting a price on a backup iZettle unit and asking if I can examine the card....them quickly tapping contactless. But most of the time the bilkers have a cancelled or non-contactless card.
You must remember, you may compromise your safety and put yourself at risk, by getting out and entering/leaning into the passenger compartment.
So you need to be extremely aware of the type of passenger you are dealing with.
Personally, I always turn the dash cam round to record what's happening (for my own safety).
Unfortunately, a problem has now emerged in connection to this type of fraud, in the form of non-attendance by police. Yet if you were to lock a passenger in the Taxi and take to a police station (assuming you can find one open at night), you are at risk of being charged with false imprisonment.
Last night a friend came into Camley Street saying he had just suffered an expensive bilk (£32). He'd taken a lady to Colbrook Row in N1, where her card had not been accepted by his rear fitted CC reader. She insisted there was nothing wrong with her card and that it must be his terminal at fault. She added she had no cash.
The driver said "in that case I'll take you round to the cash machine", which she agreed to.
But once there, she got out and said "I've tried to pay you, it's your fault not mine". Refusing to use the ATM, she just walked away.
The driver called the police saying he had been bilked but was following the passenger who had now become aggressive.
To his surprise, after taking 'all' his details -including his birthdate, home address, registration and badge number- the emergency operator gave him a case number and said they would call him back within 48 hours and that they wouldn't be attending the scene in person.
This is the price we are paying for Khans toilet facilities for bus drivers....£6m spent on super-loos for bus drivers, while closing down London police stations and reducing the amount of officers to raise the cash.