UK armed police shot and killed and unarmed, innocent man in 2005. Nobody was charged or had to justify their actions in court. It happens far less often but when the situation does arise, it's not obvious British police are better trained and react better. What does work is the policy of restricting both firearms ownership and the number of armed police.
The fact that you didn't even need to know his name and most in Britain know who you're talking about says all you need to know about the scrutiny of it. Every time a British police officer discharges their weapon it is automatically investigated by the Independent Police Complaints Commission.
No, that doesn't, in itself, say anything about the degree or quality of scrutiny. It just says the events are so rare, they're memorable. Officers discharging their weapons are reviewed in the US as well.
If you're referring to the Jean Charles de Menezes shooting, then there were weeks of hearings where the police and officers involved had to justify their actions.
There was a very long coroners inquiry on this shooting. In this coroners court the shooters had to explain in details. Yes, they got the identifications wrong, but this was not after some random telephone call, but after four suicide bomber had filled dozens of people.
I think the balance is about right and nothing like the USA. More importantly the jury of peers, in the coroners court, thought the Met Police failed on Health and Safety grounds but not the individual shooters.
There are long inquiries and court cases in the US as well. Jury of peers, the whole lot. I'm not sure how the 'balance is about right and nothing like the USA'. When called upon in a moment of crisis, these people got onto a train and shot an innocent person in the the head half a dozen times, from close range.
The big difference is, there are fewer opportunities for armed police to screw this up. There are far fewer of them (heavily armed police are the exception, rather than the default) and they are not nearly needed as often (the citizenry is not as heavily armed). The policy that largely prevents the mistakes is what really helps, rather than having better armed police or better post-cockup inquiries (both of which, to me, seem fairly debatable).
