You don't see Darwin or (Free)BSD in the Apple website. You do not see win32, winRT, NT kernels in a microsoft website. You do not see Linux in Android sites. Ubuntu is itself a known brand. Not having the word 'Linux' in its site proves nothing. Linux is a part of Ubuntu. You don't see GNOME, X, and other parts of Ubuntu mentioned there. People who know about Linux already know Ubuntu is a Linux distro same as android. People who doesn't know Ubuntu is Linux will learn it later using it.
It doesn't matter if people know what's underneath. It matters people use best quality Open Source System. Ubuntu's target is always general people. Having said that, here's some 'Linux' word in the site: http://www.ubuntu.com/about/about-ubuntu -- M. Nasimul Haque Appliansys, Coventry, UK http://www.nasim.me.uk -- Ubuntu Bangladesh https://lists.ubuntu.com/mailman/listinfo/ubuntu-bd
