The Head of the Repair Certifiers Association says the vehicle industry has been left unsupported for years.
Tony McHugh said the agency was out of touch with the industry and that had left it in a dangerous place.
The Transport Agency has apologised for failing to enforce safety rules in many inspection areas, including warrants of fitness for cars.
The agency admitted knowing for years that a mechanic in Dargaville was not doing proper checks, and only clamped down after a fatal car crash.
"We just need to get rid of some of the shonky places, or we need NZTA to do the audit processor with more stringent controls and then support the industry," Mr McHugh said.
"It's been left on its own for far too long and it's a dangerous game when you're playing like that," Mr McHugh said.
The previous National government let the vehicle industry run itself and the current government has discovered they need to increase their support and regulation of the industry, Mr McHugh said.
"This government has now found out that they need to regulate a little bit more and they need to support the industry more, which I think they are starting to realise and are working towards that path," Mr McHugh said.
National's Associate Transport spokesperson Brett Hudson said public confidence in the agency has been completely undermined.
"It's actually important that the public retain or regain the confidence in the system and in NZTA, that's got to be the first focus."
NZTA comes under Parliament's scrutiny twice a year at select committee and the transport minister has oversight of the agency. But Mr Hudson said to his knowledge these problems were not raised in the time National was in power.
It was only last month that the Transport Minister Phil Twyford expressed his disappointment at NZTA when it was revealed they hadn't been carrying out proper checks on vehicle safety certifiers for the last two years.
Independent lawyers were called in to review 850 compliance files and at the time Mr Twyford ruled out heads rolling as a result of the blunder.
Last night he wouldn't comment on what his staff are calling "NZTA employment matters" but said in a statement the NZTA had failed in its regulatory responsibilities.
"I'd like to express my deepest condolences to the family of William Ball," he said.
"The failure by the NZTA to not uphold its regulatory responsibilities to the standard I expect is completely unacceptable and shows why Meredith Connell was called in by the board to investigate earlier this year."
New Zealand First transport spokesperson Clayton Mitchell said New Zealand had some of the best safety checks and processes in the world but it was clear there had been failures that needed tightening.
"Anything you do in life I guess where there's human intervention you have human error, we've got to make sure that we do get it right, so to go back and check up on this is the right thing to do, it's going to carry the cost that's going to cause the eyebrows to lift."
Mr Mitchell said there was a lot of questions still unanswered but ultimately the buck stopped at the top.
Transport Agency chairman Michael Stiassny told Morning Report the organisation had let New Zealanders down, but had taken steps to improve.
The agency had been taking an educational approach, rather than ensuring the regulatory processes were at the best practice.
"We have taken steps to improve and to continue to improve the service and the regulatory processes we have, so that New Zealanders can be comfortable that we are getting better at this and as we go through this change we are moving towards and will end up with world-best practice."