Most of the native Mac OS X applications are made using XCode which comes with the same basic default menu each time you start a new project. That is a guarantee that most apps are going to adhere as much as possible with the OS's conventions. There are exceptions, of course.
How many different IDEs/toolkits are available and used to develop Windows or "Linux" applications?
How many different IDEs/toolkits are available and used to develop Windows or "Linux" applications?