It is true. In the first two days of this discussion, witnesses were interviewed and discussed here. A man and his children drove by the stranded van around 3:30PM. He asked the couple if they needed help. They did not need any help. This is not the mechanic, who also asked if they needed help.
Twenty minutes later, this same man's wife drove by and the couple were still stranded on the side of the highway. She had a car full of relatives and did not feel safe stopping on the highway because there was oncoming traffic in both directions. She contacted RCMP and notified them about the van at the side of the highway. We know that RCMP were 4 hours away, and they probably assumed that by the time they checked out the van, it would be gone.
RCMP responded to a call at 7:19AM the following morning, when they learned that there were two victims next to the van.
All links can be found in the first couple of days of this discussion - back on July 19.