How often have police needed to use them at a station or airport
It seems to me that making the traveling public unconfortable is not worth it
I am not likely to be shot as I always pay the correct fare but I do not like to feel stalked by gun tooting coppers
I think the police need to have relaxition training I was at Buckingham Palace and went to ask a copper what regiment the guards were they were wearing blue burries, this copper went into panic mode he shouted stand back back off I do not think I look too dangerous I am 66 white but do have a grey beard---------Over reattion I will not try to speak to a copper again !!
Relevant attacks (casualty figures exclude perpetrators):
Lod (Tel Aviv) Airport, 1972, 26 dead, 80 wounded. Attack halted by Armed Police.
Paris-Orly Airport, 1978, 1 dead (a policeman), 3 wounded. Attack halted by Armed Police.
Esenboga International (Ankara), 9 dead, 72 wounded. Attack halted by armed Security Forces.
Vienna Airport, 1985, 3 dead, 39 wounded. Attack halted by Armed Police.
Rome Airport, 1985, 16 dead, 99 wounded. Attack halted by Armed Police.
Los Angeles Airport, 2002, 2 dead, 4 wounded. The single attacker was halted by two Security Guards, one armed, one unarmed.
Chhatrapati Shivaji Railway Station, Bombay, 2008, 58 dead, 104 injured. No intervention until the attack was over. 5 police officers, in addtion to the figures above, were killed trying to stop the perpetrators outside the station. Just two men were responsible. Attacks elsewhere brought the toll to 164 dead and at least 308 wounded.
Kunming (China) Railway Station, 2014, 28 dead, 118 wounded. Attack was carried out by 8 men with knives. Police not on scene but halted the attack once they arrived.
With regard to your encounter with the armed policeman. The Lod Airport attackers were Japanese, Nicky Reilly (failed Exeter attack, 2008) is a westerner, as is Richard Reid (failed 'Shoe Bomb' attack, 2001). Oh, and you seem to forget that Radical Muslims are not the only terrorists around, there is the small matter of Dissident Irish Republican terrorism and a few other sources beside, including people like David Copeland who come right out of left field.
By the way, people guarding things don't like being distracted, their job is to be watching for threats, not acting as an enquiry service. Neither do people carrying weapons like people coming close enough to seize their gun, either in order to prevent them using it or in order to get hold of it an use it. No doubt he would have been the usual friendly Copper once he had finished the job and locked away his gun, but in the meantime he was in a high threat environment and had a job to do.