I'd love to see some hard evidence of that claim.
It's a tragedy of the commons. Daily Mail readers like parent poster are convinced the country is going to the dogs. Since many of them have the power, money and/or influence to do some small thing such as set up private CCTV surveillance of public land, or deny public space to a disenfranchised group (only by ageism of course - watch for a proper fight if they try this on a race-related basis), between them they can damage our public spaces and society. The same people will write the council demanding double yellow lines outside their house, and write to the council bemoaning lack of on street parking near their favourite shop.
Eventually you end where we are now - with local councils using anti-terroism laws to create mini intelligence agencies for the school admissions system. That is not a joke. Google it.