People think tazer guns are some sort of magical device that knock people out. A month after this Tulsa incident, in chicago, a man high on PCP was tasered multiple times during an arrest and still beat the shit out of a female cop. She was knocked unconscious and required reconstructive surgery.
http://www.nbcchicago.com/news/loca...ting-of-Chicago-Police-Officer-397152341.html
If you watch the arrest video above, and the dashcam / heli footage from this Tulsa incident, the issue is imo less a question of "should cops shoot people they fear" and more an issue of police procedures during arrests. Everything is always constantly getting escalated, instead of focusing on de-escalation. Well, if you are always escalating things - yelling and screaming at suspects, going in undermanned, approaching them instead of letting things cool down, etc - then things are going to get to the gun shooting stage really quickly.
In places like NYC and LA you see police training now tends towards more de-escalating and defusing situations rather than the tense "us or them" mentality that still pervades 90% of US law enforcement jurisdictions.