Backspace in Google Chrome not "back to last page"?
Solution 1:
It really is a bug. See this issue in their bug tracker.
Solution 2:
The mac version of Google Chrome is a Developer Preview i think. So there are many bugs and many issues to fix to get it on par with the windows version.
Solution 3:
I can tell you that in the current version of Chrome on windows the Backspace works fine (I never knew about that binding, by the way). So I'd assume this is just a bug in the beta.
Solution 4:
Maybe you should better use Cmd-[ and Cmd-] to navigate back and forward. This also works in other browsers and in, for example, Finder.
(While awaiting the bug fix, and if Cmd-[ and Cmd-] are too difficult on localised keyboards: Cmd-Left and Cmd-Right might work in Chrome as well. These don't work in Finder though. And see Can I seize control of Cmd-Left in OSX? here on Super User, or Disable Firefox's Command-Arrows page jump shortcuts on macosxhints.com for an annoying issue in Firefox for Cmd-Left and Cmd-Right, which may unexpectedly take you to the previous page while editing! Likewise, using Delete may cause problems in other situations. So one may actually want to disable Cmd-Left, Cmd-Right and Delete to work for navigation, like described for Firefox in those links.)
(As a side note, a Mac does not really have a Backspace key.)
Solution 5:
I use the gestures with Chrome and those seem to work. Use three fingers and swipe to the left. This will take you back to the last page. Obviously doesn't work well with a mouse, but nice that the Chrome team has it implemented.