According to this article, Canada rejected her entry as well. Maybe it's not just the US, but this person actually had a real issue with her visa and her travel plans were not prepared well.
"...when she reached the border [Canada], Mr Burke said the Canadian authorities denied her entry as they were concerned she may try to work illegally."
https://www.bbc.com/news/articles/c80y3yx1jdyo
"...when she reached the border [Canada], Mr Burke said the Canadian authorities denied her entry as they were concerned she may try to work illegally."