Bus drivers have been told they should always carry passengers who want to pay with bank notes, even if they don't have enough change.
The safety message comes after a Tauranga driver was blasted for refusing to let a child on board because the boy had only a $20 note to pay his $1.80 fare.
Unions representing drivers said the female driver should never have left the passenger behind.
Bus driver Kay Pridmore was issued with a warning last October by her Tauranga-based employer, Go Bus Transport after leaving the child behind.
She later told her boss: "I am not a f***ing banker, if I wanted to give out change, I would work in a f***ing bank."
The story sparked a huge reaction from Herald readers who said they had suffered similar experiences.
Kevin Nolan, 45, of North Shore, said he got an apology from NZ Bus after he complained that a driver abused him after he boarded a bus to Auckland city with a $20 note.
"If they are looking to persuade the likes of me into using public transport, they need to buck their ideas up on their customer service skills," he said.
Nicky Labuschagne, a 42-year-old theatre administrator at Manukau SuperClinic, said she was often spoken to rudely when trying to pay her fare with notes.
"The drivers have been downright rude and embarrassing to the point I was in tears at the way I was treated. One driver even growled at me then spat out the window and told me to sit down."
Another New Zealand Herald reader said she wasn't let on with her baby in a pram on a Gossamer Drive to Botany trip because she had only a $20 note.
Chris Darby, chairman of the Devonport-Takapuna Local Board, said he had received individual examples to reinforce his concern that there are "too many bus drivers across Auckland who are turning young people off taking the bus by unlawfully denying them access".
"If we do not make public transport welcoming to our young people we risk losing their custom for life. In Auckland that means more cars on our roads and more congestion."
Ms Pridmore took Go Bus to the Employment Relations Authority (ERA) after claiming the warning over her behaviour unjustifiably disadvantaged her employment.
Her case was thrown out, with the ERA saying it was company policy to always give children passage even if the driver did not have the appropriate fare.
However, it was recommended that the company issue guidelines on how drivers were to deal with $20 notes. She has kept her job.
Go Bus regional operations director Darryl Bellamy was unavailable for comment.
NZ Tramways Union spokesman Gary Froggatt said drivers were never supposed to leave children behind.
"That's a real no-no because there's a risk of something happening to them."
But he said some passengers had the drivers on on a daily basis, turning up with $50 or $100 notes.
First Union Transport/Logistics spokesman Karl Andersen agreed, but said problems arose if a bus inspector found a passenger without a ticket.
"The inference taken is that the driver has taken money off them and not issued a ticket and put the money in their pocket."