Police in North America are immune to prosecution anyway
but tasers give them utter freedom to "give back" to the community when they feel like a suspect has given them a hard time...or when they are in a bad mood.
Since tasers are (officially) non-lethal, an officer can always says that he was just trying to "calm down" the suspect and no harm was intended.
Of course, most officers have never had a significant electrical shock, let alone a taser shot. Certainly not the three-times-in-a-row-and-in-handcuffs version they offer to the public.
Yes, police need to use force at times. Tasers are used for fun and for revenge.
In Canada, we have more civilians killed by police tasers than were killed by police guns previously. Of course the deaths can't be directly attributed to the kilovolts administered.
Death by coincidence, no?