If I'm using this module in FreeBSD as a non-root user, a good username but bad password will pass. Note a bad (non-existent) username will fail as expected. As root, the authentication works correctly.
[vagrant@vagrant-bsd93 ~]$ env LOGNAME=vagrant python -m simplepam // bad pwd: foobar
Password:
True
[vagrant@vagrant-bsd93 ~]$ env LOGNAME=foobar python -m simplepam // bad user, bad pwd
Password:
False
I expected that the bad password should fail. Or if root access is required, then all authentication checks as non-root should fail.