For one it is actions you are relying upon preventing, not people. There will be no prior record in first time offenders. Masks (even if they must be a head box

For one it is actions you are relying upon preventing, not people. There will be no prior record in first time offenders. Masks (even if they must be a head box to obscure shape) defeat facial recognition. So if it cannot be relied upon to stop somebody from say, tossing a lit molotov into a crowded parliament, or a suicide bomber what good is it?