The OP said "Hi, I am trying to use a PHP script as a test for a cron job.", not accessing a PHP script (or other URLs via HTTP(S)) on a remote server in a cron job.

They are totally different things. Usually, what a cron job does is not something that should be accessible on the public Internet. If someone use your scheme to run a cron job with a http://localhost/... URL, that means the script is there for everyone on the Internet to execute (provided he/she knows the URL), no matter you like it or not.