Mrs Davies, 69, had pulled to a stop for roadworks on State Highway 1, at Karapiro, south of Cambridge on January 30 when Carter's vehicle crashed into the back of her car.
Mrs Davies died in Waikato Hospital two days later.
Crown prosecutor Rebecca Mann said members of the public had reported Carter's "erratic" driving to police as she drove from Tauranga to Hamilton on State Highway 29.
Her vehicle was seen crossing the centre line which caused trucks to swerve out of the way.
A witness phoned police when she came across Carter's vehicle at the intersection of SH29 and SH1, describing her driving as "a bit wobbly on the road".
Major roadworks were being carried out between the Cambridge Golf Course and further south at the intersection of Hickey Rd as part of the Cambridge section of the Waikato Expressway, where northbound traffic had come to a stop.
Mrs Davies was sitting in her Toyota Echo which had its brakes lights on.
She suffered multiple broken bones and suffered numerous arrests in Waikato Hospital before dying two days later.