this is a very interesting question.
I can tell you more about the things I know, namely the foodsharing and -saving part, which has the following types of data:
- Members (name, address, roles, food pick up statistics)
- Messages (private 1-on-1, group chats, forum, pinboards)
- Food baskets (temporary points where people privately offer food to others)
- Stores (places where verified foodsavers pick up leftover food from supermarkets & co - a store has a team and a calendar of pick up dates)
- regional (country, state, city, district)
- working groups (e.g. big store chains, cargo bikes, development)
- Events (meetings, festivals)
- Fair-Teiler (public fridges)
Public data are the Food baskets (created by an user) and the Fair-Teiler (created by a group). I think it's completely fine for everybody to license them as Public Domain or under the Open Database License.
Due to legal and confidentiality requirements, most of the data (stores, group content) is not visible to the public. Instead, we have the status of verified users, who have access. They are told not to leak data.
The process of verification as in foodsharing.de: the user registers, passes a quiz, agrees to a waiver of food liability and completes some (currently 3) pick ups with other foodsavers. An ambassador of the regional group then verifies the correctness of the personal data.
This is the current working process of ~15.000 people in foodsharing.de since ~2 years. Less barriers and less hierarchy are wishful and can be achieved with a careful approach.
(I didn't forget about the Who's who page, hope to do it soon!)