They only interviewed survivors.
It excludes people who were dragged off into the woods and eaten.
There were probably quite a few of those before literacy became common and bear attacks a newsworthy event.
For the past 150 years, I am confident very few people were killed and eaten without anyone recording it.
It is possible, of course. As we have entered the digital age, information is transmitted and recorded much more rapidly. Investigations are quicker. So, it may be some such cases happen, but they are extremely unusual, in my opinion. We cannot know what cannot be known.