There are good pet parents who have fenced yards, and bad pet parents who have fenced yards:
I have a fenced yard, but in 15 years, my boy never went outside alone, not once. Whether it was raining, or -15F, I always went with him. I have a chain link fence with a bottom rail, and a padlock on the gate.
In contrast, a neighbor had a fence with an insecure bottom and an insecure gate. Her dogs regularly got loose, and she never did anything to fix obvious flaws in their fence. The end result was that one of her loose dogs bit someone in the neighboorhood. (They have since moved.)