Police say Rutherford, 35, of Frankton, was driving on State Highway 6 near Arrow Junction on November 30 last year, when she briefly took her eyes off the road.
She looked back to see the vehicle in front had stopped while still partly on the road and was unable to react in time to avoid a collision.
The impact caused its male driver to suffer a concussion and two head lacerations, which needed to be closed with stitches and skin glue.
The defendant, who also sustained injuries in the crash, admitted a charge of careless driving causing injury.
Rutherford opened the Kiwi Water Park inflatables attraction on Lake Dunstan, near Cromwell, in 2020.
The following year, in a by-election, she made an unsuccessful bid for the Queenstown-Wakatipu ward seat on the Queenstown Lakes District Council.
At Rutherford’s sentencing in the Queenstown District Court yesterday, counsel Tanya Surrey asked Judge Murray Hunt for the discharge without conviction on the grounds a conviction would affect the defendant’s ability to operate her businesses.
She would face barriers to travelling abroad and a conviction would bring "general stigma".
Ms Surrey also asked Judge Hunt not to impose a driving disqualification, as Rutherford needed to drive to operate her businesses and support her mother.
The accident was the result of a "terrible mistake any of us could make", Ms Surrey said.
The defendant had participated in a restorative justice meeting with the victim, and was "utterly devastated" by the crash’s impact on him.
Judge Hunt said Rutherford’s lack of attention had been "momentary", and noted she had no previous driving convictions.
"However, your plea indicates your acknowledgement it was your fault.
"I’m sure this experience has been a salutary reminder of the importance of being careful and constantly vigilant when you’re driving."
He considered a discharge without conviction was appropriate, and did not impose a disqualification.
Her ordered her to pay the victim $4000 in reparation.
