Does Linux do that to? I know Windows XP doesn't (or I haven't figured out how).
What happens is that you are actually launching a terminal application. So you can launch whatever editor you want. I'm using Ubuntu Linux, and AFAIK, it doesn't come with emacs installed. Note that emacs is usually used in graphical mode. I think by default OS X has only text mode emacs installed i.e. you can only run it within the terminal.
The other thing is the command-line editing mode of your terminal. Emacs key bindings are the most common default. So for example
someprompt>cp A B
You move to the end of the line by pressing C-e, to the beginning by pressing C-a. Etc..
However, you can put you command-line in vi mode:
someprompt>set -o vi
Then the equivalent would be Esc, followed by 0 to get to the start of the line, $ to get to the end. Etc..
set -o gives you the current shell settings. set -o emacs puts you back into posix.
The main reason I'm not into emacs is that it's a modeless editor. I hate chording multiple keys for the most trivial things. Vim is a modal editor, so you just get yourself into command mode, and almost all commands from then do not require modifier keys.
In conclusion... Emacs is probably best for writing non-programming text.