- Which other Meta badges are (un-)attainable?
- For the unattainable ones, why do they still appear under the list of Meta badges?
Reputation related badges
Reputation on meta isn't shown, so it's hard to see what happens. Reputation related badges can be achieved, as several people got the Mortarboard badge. Nobody has Epic or Legendary yet, but it should be possible as well.
Badges which we cannot get on meta:
Bounty related badges
You cannot start a bounty on meta because of missing reputation system.
It seems that the chat is considered only for the main site.
meta.SO has its own chat, so there are people with such meta badges.
Site proposal badges
Those badges were not given at the start of the site, and now it's too late.