Their father, Grant Roberts, died in a 2012 crash caused by a visitor who had been in New Zealand for one day.
In the select committee room in Bowen House in Wellington, Sean, Cody and their mum praised industry moves such as a code of best practice and more information being made available to drivers, but politely asked for the extra step of a competency test.
In May, 25 rental companies announced the trial of a new code of practice, in which drivers have to fill out a questionnaire.
If they do badly, they could be asked to do a trial drive.
That was followed by the Automobile Association (AA) launching an online driving simulator for tourist drivers in November, and this month the NZTA announced a $25 million funding boost for tourist driver safety initiatives.
Amidst the heat of last summer's overseas-driver debate - with keys snatched and even an assault - Sean and his family's advocacy was both powerful and measured.
After the select committee appearance, Ms Pipson confided to a friend how nervous she had been, while Sean fielded more questions from media.