I imagine there's also got to be a difference between getting it for a planned surgery that you can prepare for, vs having it thrust on you suddenly during a traumatic and painful experience. Kind of hard to let go in that situation.
An arrest sound like one of the worst set and settings to get dosed with ketamine. The person being arrested might not know what they were injected with. The person might not trust the police. The person is being detained against their will.
And several doses of morphine usually have at least some effect on the body/mind