I am not sure that it is true...one of my good friends who lives down the road from me has family in Virginia and San Diego. He has visited both in the past 6 months and I asked if border crossing was a problem and he replied no. He flew to San Diego and drove to Virginia.
As it turns out some family members of his are arriving this evening from the US to visit him. I will ask if they had to produce a passport at the border.
Hopefully the answer will be no.