Well, my question was not about things OpenStreetMap does (and does quite well). My question was about something it does not provide at all. Why haven't similar communities in other big cities across the world created similar sites (“own/better Wikimapias”) to collect information on everything they find interesting in their neighborhoods? Seemingly useless pedestrian bridge across highway is a perfect case. Maybe they did, and I haven't found those? Hopefully, my examples show that such projects can slowly grow into enormous treasures.