Because anti wolf hunting advocates pushed it using false info saying it would cause more wolves killing dogs. From what I understand from talking to bear hunters most dogs have been attacked during the training period at which time the wolf is still heavily defending the young of the year and territories. You don't see the issue during the late fall early winter with the cat and coyote guys that use dogs. Most dog guys I've talked to would love to go after the wolves with dogs, hopefully they can in the future. I also believe the dog guys were the sacrificial lamb to keep the lawsuits away.