Well, given that plod couldn't stop a policeman out on bail for murder of his wife, then going out and killing the witness (his mother-in-law) and himself.....
Life is a risk, but our leaders are totally risk-averse. They cannot conceive that things can go wrong.
Let's take an example - the British Grand Prix is stopped because a press helicopter crashes on the grandstand at Club corner. A tragic accident
Or a helicopter flies into the grandstand at Club corner - a terrorist outrage
Same loss of life, but either could happen.