v$sgastat pools appear per con_id, but not the buffer cache

One buffer cache per instance IS reported:

SQL*Plus: RELEASE 12.1.0.2.0 Production ON Sun Oct 4 15:34:44 2015

Copyright (c) 1982, 2014, Oracle.  ALL rights reserved.

Connected TO:
Oracle DATABASE 12c Enterprise Edition RELEASE 12.1.0.2.0 - 64bit Production
WITH the Partitioning, Automatic Storage Management, OLAP, Advanced Analytics
AND REAL Application Testing options

SQL> SELECT pool, NVL(pool,name), COUNT( DISTINCT con_id) FROM v$sgastat GROUP BY pool, NVL(pool,name) ORDER BY 1,2;

POOL         NVL(POOL,NAME)             COUNT(DISTINCTCON_ID)
------------ -------------------------- ---------------------
JAVA pool    JAVA pool                                      1
large pool   large pool                                     2
shared pool  shared pool                                    4
             buffer_cache                                   1
             fixed_sga                                      1
             log_buffer                                     1
             shared_io_pool                                 1

7 ROWS selected.

Shared pool components break OUT BY container:

SQL> SELECT con_id, pool, name, bytes FROM v$sgastat WHERE name = 'SQLA' ORDER BY con_id;

    CON_ID POOL         NAME                            BYTES
---------- ------------ -------------------------- ----------
         1 shared pool  SQLA                         32205512
         2 shared pool  SQLA                          1476168
         4 shared pool  SQLA                         35735376