The Transport Agency has stopped multiple mechanics and garages after finding a raft of non-compliance issues.
There are just 20 people responsible for checking up on those carrying out warrant of fitness checks, which is around 12,000 garages and mechanics.
Andrea Andrew is a Warrant of Fitness consultant and has been in the business for 16 years - she said the Transport Agency compliance officers she worked with were doing all they could to keep people safe.
"I'm sure that they're seeing on a day-to-day basis that these people have been non-compliant for some time and that they've been actively trying to do something about it," Ms Andrew said.
She said there weren't enough officers to deal with the huge workload of monitoring all of the garages and mechanics issuing warrants.
"They are the face of NZTA on a day-today basis, so I would imagine that they are the people that everybody's looking to for these problems, instead of maybe higher up."
Checkpoint has spoken to several NZTA compliance officers who said they had complained to their managers in the past about safety, but their concerns weren't followed up.
One compliance officer, who wished to remain anonymous for fear of losing his job, told Checkpoint the three-step model of Identify, Educate and Deter, is too soft and that some garages haven't been inspected for four years or more.
NZTA declined requests for an interview on Checkpoint.