The Transport Ministry says the risk to bus drivers is not great enough to justify making security cameras compulsory in buses.
The Tramways and Public Transport Union has called for the move following the death of a bus driver at a Lower Hutt bus depot on Friday night.
Herman Curry, 64, was found unconscious near his bus at the Waterloo interchange and died shortly after. His cash box was taken and four young men have been arrested for theft.
Taxi cabs have been required to carry security cameras since August last year.
Land Transport Safety manager Leo Mortimer says buses carry more passengers than taxis and do not operate at such late hours.
"A lot of the buses already have cameras in them. So we thought for the buses, it was more an issue of having a wider health and safety approach to the bus area than just simply putting a camera in a vehicle."
Mr Mortimer says it is up to the employer to ensure that its drivers are safe.
Police are waiting on final post-mortem results before declaring the definitive cause of Herman Curry's death. However, interim results indicate that he was not assaulted.
The Tramways and Public Transport Union says about five drivers a year are attacked for money ant it will continue to put pressure on the Government for security cameras in buses.
Union national secretary Gary Froggatt says drivers can also be assaulted for arguments over fares and security cameras would help to monitor the situation.