If you were to log in, you'd be able to get more information on your fellow community member.
My experience with "four buttons being available at all times and always in the same place", based only on the devices owned by my friends: - Motorola Milestone has back, menu, home and search; - Motorola Defy has menu, home, back and search, and the menu icon is very different between the two devices. - SonyEricsson Xperia X10 has menu, home and back but no search. I don't know the Android ecosystem enough to argue about the reasons for these but from a user's perspective it's annoying.