The taser has to make contact. The other problem is hay there have been deaths from tasters, too, so some departments have scaled back on their use.
Conversely, a lot of times a taser won’t stop a really hopped up person. I remember a case where a crazy old woman attacked her family with a knife, they barricaded themselves in a room and screamed for help, the police arrived and the old lady charged them. They tased her and it didn’t even slow her down. One of them shot her just as she lunged at him.
Oh - and when the family got out of the room, guess what they did? Claimed police brutality. What else?
The local PD has recently had two Taser failure-to-fire incidents while at the same scene. The officer recounting the story to me was on the scene and said the individual was lucky not to be shot. The officer told me he was beginning to press the bang switch when the suspect got smart and gave up. The malfunctioning Tasers were checked out and returned to service.