Im pretty sure that many players are VERY aware of this but when im a cop and i find a wanted player, i hit and tazer them multiple times but they dont get arrested.
Arresting and killing the wanted player is not the same thing. When you kill a player no matter in hitman or cop mode, they return back to spawn. When you arrest them, they go to jail. It just sometimes takes multipel hits with the stun gun to arrest a player.