Because it'd be very hard to compare short program length otherwise? 5 LoC says nothing.
But yeah, for C the LOC metric can be gamed to a silly degree
Python does have a "semicolon to combine multiple statements", and has further (lambda f: f(f)) expressions for complex expressions with local names and scopes.
(not that using either for those would result in pythonic code, but it is certainly not missing from the language)