You appear to be making assumptions based on the Windows OS which don't apply here, which confuses me as you seem to be saying you use Linux.

Both Ubuntu and Mac OS X have a top "bar" which has functions in both the top-left and top-right corners, easily accessed according to Fitt's Law.

In Ubuntu top-left and right are Applications and Logout/Sleep etc. respectively and in Mac OS X it's the "Apple" system menu and Spotlight search. Maximised windows in both these OS's don't expand to the top corners and in Mac OS X windows don't even "maximise" to the full size of the screen, rather optimising for the correct size which will often not be full screen.