pg_basebackup copies the data directory permission mode from the upstream server. But it doesn't copy the ownership. So if say the upstream server allows group access and things are owned by postgres:postgres, and I want to make a copy for local development and make a backup into a directory owned by peter:staff without group access, then it would be inappropriate for pg_basebackup to change the permissions on that directory.
-- Peter Eisentraut http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
