Python's culture heavily encourages explicit, consistent code while Ruby's culture is a lot more flexible in that respect. Rails makes many assumptions by default and has an API that is based on clever coding for the sake of maximizing productivity. That stuff would likely not fly in the Python community.
There are some of us Ruby users that find the Rails approach absolutely disgusting... I don't believe it maximize productivity either - the moment you need to deviate too much from the defaults you quickly descend into hell, trying to figure out what "magic" is happening behind your back.
