The union representing security guards says the industry is full of companies "trying to undercut each other" and lower prices.
A 17-year-old has been charged with manslaughter following the death of an Allied Security guard at Countdown Papakura on Thursday.
He was assaulted and reportedly punched in the head, Stuff reports.
E tū Industry Coordinator Jill Ovens says Allied Security took over the Countdown contract from First Security last year.
"Allied Security doesn't engage with the union at all," Ms Ovens told The AM Show.
"We try to initiate for bargaining to get into discussions about things like health and safety and training which would protect the guards more. But they refuse to engage with the union."
Ms Ovens says it's a "really tragic" outcome for the man, who was likely earning minimum wage.
"The mandatory training that they have to do to get their licence is very very limited, one or two days. There is an element of how to handle conflict but that's the main role they have. They have no powers like the police do to arrest or anything like that.
"We're doing a training programme with employers like Armourguard and First Security. When we asked Allied to be part of this to upskill their staff, they said that if the client requires them to have an NZQA qualification, they just go and hire someone whose already got it."
The teenager charged with the death was expected to appear in the Papakura District Court on Thursday afternoon.
Newshub has approached Allied Security and Countdown for comment. A spokesperson for Allied Security said it would respond later on Friday, but for now is "focused on our team and the family".
Ms Ovens says it's the second serious assault on a security guard within the past week.
A guard was also attacked in the Accident and Emergency Department at Auckland Hospital last Friday.
"This is a sobering reminder of the vulnerability of security officers," Ms Ovens says.
She says the union is working with WorkSafe New Zealand and the New Zealand Security Association on best practice guidelines for health and safety.
Watch the full interview with Jill Ovens above.
The AM Show with Duncan Garner, Amanda Gillies and Mark Richardson, weekdays 6-9am on RadioLIVE and streaming live to the rova app on Android and iPhone.