I wouldn't have believe it if I didn't see it. The backup file does include administrator passwords. That's why I was always able to login after a restore using my previous credentials.
While going through a restore, again, I was just reading through the documentations and came across this:
In addition, you have the option to encrypt the backup (Triple DES encryption). Once you have selected this option, provide a password (second time for verification). You will be asked for this password when importing the backup (the file extension for encrypted backups is ebf).
Note – A backup does include administrator passwords as well as all RSA keys and X.509 certificates. Since this information is confidential, it is good practice to enable encryption.
