Mac OS X used to be the one of the easiest operating systems around to get a basic web development setup. For anyone interested in learning HTML/CSS/JS etc, all they had to do was open the sharing pane from system preferences and enable the web sharing option. On OS X 10.9, web sharing has been removed.
That doesn’t mean apache isn’t installed, by default. It is, its just hidden away waiting to be manually invoked using a Terminal command.