Autovacuum in Postgresql database
Autovacuum only runs when necessary:


if too many rows have been changed or deleted sine the last VACUUM run
if there are rows old enough that they should be &ldquo;frozen&rdquo; to prevent data loss due to transaction counter wraparound.


See the documentation for details.

If autovacuum never ran on some tables, that could also be because there was no reason for it to run yet.