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?

>>39
λ is too short for something that powerful.

>>39
function and lambda are both way too long. honestly I bet half of all CL macros are just sugar to avoid having to type lambda.

>>42
I find lambda acceptable in call-with-*/with-* functions, but yes, most of the times it's too long.