On a completely separate note, I would love to see small infra-red LED devices which people can wear that would disable a smartphone's camera/recording capability. I know this technology is nothing new,
Apple patented this idea and one of the intended purposes was to prevent recording at concerts, theatres etc...
Given that it's not unlawful to record anyone in a public place, it would be a great way to protect your privacy nonetheless. Regardless of what the law says, while I cannot physically grab someone's phone or force them to delete data, I should be able to choose who records my image and if that means disabling their camera while it's pointed in my direction, then this is something I'd love to see.
It could be incorporated rather seamlessly into clothing, accessories, bags etc...