To me, the fact that m = max(s) if s else default doesn't work with iterators alone makes this worthy of consideration.   

I would also note that min/max are the only reduction functions that don't have the ability to work with a possibly empty sequence.  For example:

    >>> sum([])
    0
    >>> any([])
    False
    >>> all([])
    True
    >>> functools.reduce(lambda x,y: x+y, [], 0)
    0
    >>> math.fsum([])
    0.0
    >>>