I installed Nginx using homebrew and after completing the installation the following message was displayed:

In the interest of allowing you to run `nginx` without `sudo`, the default
port is set to localhost:8080.

If you want to host pages on your local machine to the public, you should
change that to localhost:80, and run `sudo nginx`. You'll need to turn off
any other web servers running port 80, of course.

You can start nginx automatically on login running as your user with:
  mkdir -p ~/Library/LaunchAgents
  cp #{prefix}/org.nginx.nginx.plist ~/Library/LaunchAgents/
  launchctl load -w ~/Library/LaunchAgents/org.nginx.nginx.plist

Though note that if running as your user, the launch agent will fail if you
try to use a port below 1024 (such as http's default of 80.)

But I want Nginx, on port 80, running at login and I don't want to have to open terminal and type in sudo nginx to do it. I want it to load from a plist file like Redis and PostgreSQL do.

I moved the plist to /Library/LaunchAgents/ from the user folder equivalent and changed its ownership, also tried setting the user directive in the nginx.conf file and still the same error message in Console.app:

nginx: [emerg] bind() to 0.0.0.0:80 failed (13: Permission denied)

(along with another message telling me that since nginx was being run without super-user privileges, the user directive was being ignored)