local variables in Perl and Lua

I didnt get an answer for this in the Python thread, so I'll ask here: Why do variables have to have the local keyword to make their scope local? Why cant it just use implicit lexical scope like most any other languages?

>>21
>not the right story. Lua does it this way because it's a data description language. The designers feel that a simple file that just says "height = 50 width = 20" should be useful.
You can do the same with Lisp:
(Width 50)
(Height 20)

What is the point?