A truckers' group says drivers fear getting pinged for an expired licence or certificate of fitness.
During alert level 4 lockdown last year, many vehicles owners got official exemptions that bought them time so they did not run foul of police or insurers.
The Road Transport Forum said transport officials have told it that this time, the "small extensions" to lockdown are creating too much uncertainty to repeat the exemptions.
"We have been stonewalled," said the forum's Nick Leggett. He said he raised this with NZTA last week.
"Rule number one of crisis management is you make decisions with the information you have on the day.
"Instead, we appear to have officials overcome by timidity."
He raised the prospect of worried drivers, or managers of fleets of $700,000 trucks, being needed more than ever to support the economy, but waylaid.
"We could see truck drivers stopped at the side of the road, vehicles pulled over."
An exemption to give drivers a three-to-six-month extension to get licences or certificates delayed under lockdown in order would not impinge on safety, because truckers were bound to do daily safety checks of their rigs, Leggett said.
The forum had had verbal assurances from NZTA Waka Kotahi, but this - or relying on the police or insurers to give drivers a break - would not suffice, he added.
NZTA Waka Kotahi has been approached for comment.
The forum, which represents 3000 truck companies, is also worried that Auckland and parts of the Waikato will be left locked down, which turned into a "monumental mess" last time, Leggett said.
"We are told the department of prime minister and Cabinet and Ministry of Health will be the decision makers on this.
"We question the capability of government officials to make decisions about the flow of freight and the welfare of all the horses, bobby calves, lambs, and other animals being transported at this time."