Cassandra Watson had wanted Hamish Cox (18) jailed for his dangerous driving which caused the death of her daughter, Natalie O'Neill (19), and Caleb Trembeth (24), on November 24.
However, Judge Emma Smith in the Queenstown District Court sentenced Cox to 12 months' home detention, to be served in Dunedin at the home of a family member, and disqualified him from driving for four years.
Mr Trembeth and Miss O'Neill died from injuries sustained when the Subaru WRX car Cox was driving on November 24 slid off the road near Glendhu Bay, Lake Wanaka, while travelling around a corner about 100kmh, and smashed into a tree.
Cox and two other passengers, youths aged 15 and 17, were injured.
In May, Cox admitted two charges of dangerous driving causing death and two charges of causing injury.
Miss Watson said she felt a "lack of justice".
She and another daughter, Bernie O'Neill, had wanted Cox jailed.
Mr Trembeth's mother, Shona Turner, said she accepted the sentence, adding she could not put a price on her son's life.
During Judge Emma Smith's sentencing she had mouthed a silent "thank-you" when the four-year disqualification was handed down.
Afterwards, she said she was pleased about the length of disqualification because Cox would have to resit his driver's licence.
Mrs Turner said another of her three children, trainee teacher Nicky Turnbull (19) had died seven years ago in an accidental fall, and she had found the legal and coroner's system difficult to fight.
This time, she had been more accepting of the system.
Miss Watson said 12 months' home detention was "not enough".
"It is just ridiculous . . .
It's not going to be much of a deterrent.
Twelve months' jail would have been a real loss of liberty and closure."
Both mothers echoed Judge Smith's hope that the effects of Cox's sentence could prevent the death of other young persons.
Last night, Caleb's father, Pat Trembeth, said he did not believe justice had been done.
Mr Trembeth, an Oamaru artist and musician, believed similar incidents would continue to happen until punishments were handed out that would act as deterrents.
He believed Cox should have been sentenced to at least several years imprisonment.
The mothers said in interviews after the hearing that Cox's case proved speed did kill, even though he had been found to be going "about" the speed limit of 100kmh.
They accepted, as did Judge Smith, that drivers could ignore the recommended speed of 55kmh on that particular corner, but to do so was stupid.
"Speed does kill - that and the smack at the end," Mrs Turner said.
"Stupidity kills.
Speed just makes any accident potentially worse," Miss Watson agreed.
They intend to seek a coroner's recommendation for law changes to prevent young people getting behind the wheel of high-powered cars.
Miss Watson wants the police, ACC and Occupational Safety and Health to better co-ordinate driver training and include some form of race track training, so young people can be taught to corner properly.
She also wants a licence grading system requiring drivers to gain experience before they gradually move up to higher-powered vehicles.
Mrs Turner wants parents and finance companies to take more responsibility for the types of first cars young people are buying.
Cox and his family left the court quickly after sentencing.
His lawyer, Campbell Savage, of Dunedin, said his client and his family were "gutted" by the sentence.
During sentencing, both mothers read victim impact statements in front of a packed gallery of about 50. They spoke of their anger when they learned Cox had continued to drive after the accident.
As they described their overwhelming grief and loss of happiness, Cox maintained a sombre and calm demeanour and looked at them as they spoke.
Mr Savage said Cox felt a deep sense of responsibility, had overestimated his capabilities, and felt his actions had ended two promising lives.
"The consequences are not something he has taken in his stride, or something he is indifferent to," he said.
Judge Smith said she did not think Cox would fully understand the consequences - "not until you understand what it is possibly like to outlive a child.
That is possibly the worst event for a parent."
While Cox's victims chose to get into the car with him, they could not have got out of the car while it was travelling at 100kmh.
Cox had acted arrogantly, immaturely and with bravado, he had been careless with his victims' lives, she said.
