In this context "access control" doesn't mean what you think it does. It refers to multiplexing the communications of multiple devices over a single shared communications medium, as in "controlling" (arbitrating) shared access to the radio spectrum. It has no relationship to network authorization or authentication and provides no security whatsoever.

http://en.wikipedia.org/wiki/Channel_access_method

Calling it "access control" has always been confusing which is why people started calling it Machine Address Code or Ethernet Hardware Address instead.