why isn't laravel's php artisan serve server being accessible from the WWW on IIS
To get it to work outside of localhost, do php artisan serve --host 0.0.0.0
If you want it to work without specifying the port in the browser, php artisan serve --host 0.0.0.0 --port 80. sudo will likely be required.
Note: php artisan serve should never be used for production. It's for dev and demonstration only and won't be able to handle more than a person or two's worth of traffic.