Everyone at the festival could have been armed and it would have made no difference since the shooter was not easily visible.
Whilst evil people will always find a way of creating havoc I fail to see why this should be used as an argument to do nothing. Some of the same people who are basically saying that restricting access to weapons is pointless and an infringement of their rights to arm themselves like they are their own personal army are the same people prepared to take what Sadiq Khan said about being cognisant of terrorism in modern cities and twist it to make him seem like an apologist for jihad. They are the same people who would happily demonise a whole population and restrict the rights of innocents for the supposed sake of the greater good.
What is sauce for the goose is sauce for the gander. If fighting Islamist terrorism requires restrictions and actions that tread on some supposed rights to ensure that the rest of us can be safer in our towns and cities then why is the right of people to attend school, work or some event in safety trumped by the rights of those who have some need to walk around carrying a small arsenal just to go and buy some milk.
Just to be clear - I don't have an objection to people owning guns even simply for the pleasure of owning it. I am not under some illusion that people in the US can just go and buy any gun anywhere. I know that many gun owners are responsible people who don't have a pathological need to carry arms to make themselves seem hard.
I do, however, find it simply amazing that the US is so unwilling to try and make their streets safer, with the answer seemingly to be a constant proliferation of arms. The bad guys have guns so give the police bigger guns. The police and bad guys have bigger guns so the average citizen feels they need a bigger gun to be safe. This not to mention the local militias that exist where the government and local authorities seem happy to have self appointed armies with their own leadership wandering around pretending they are the police and army. I suppose even these guys have some credibility and structure when compared to those conspiracy theorists building shelters, making their own enclaves for when the government goes to pot.
The underbelly of latent violent potential in the US is frightening. The seeming unwillingness/inability to acknowledge and tackle this is even more so.