Some of those are "groups" or "communities". One of the features that has been requested is proper support for such accounts in a manner similar to communities on LiveJournal, but unless and until such support is added they are handled in the same manner as individual accounts.
Of course there have also been joke/bogus accounts registered, such as the first three listed here, not to mention overt troll/vandal accounts and attempts to impersonate well-known artists who hadn't registered their own account.
Some of those are "groups" or "communities". One of the features that has been requested is proper support for such accounts in a manner similar to communities on LiveJournal, but unless and until such support is added they are handled in the same manner as individual accounts.
Of course there have also been joke/bogus accounts registered, such as the first three listed here, not to mention overt troll/vandal accounts and attempts to impersonate well-known artists who hadn't registered their own account.