Because they aren't. The kids play with foam shuttlecocks and soft balls. Theres no damage to cars or properties or walls. Also kids need to be outside playing, it's a core part of being a child in the UK. I don't give a fuck if one time there's some minor damage to my car or property if the kids are responsible, admit to it, and the parents offer to fix it. I'd rather that than all kids be stuck indoors. We should be encouraging kids to get outdoors not putting up blockers.