Is it just because of dynamic typing we don't require a concept of interfaces(like in Java and C#) in python?
One key thing about at least some dynamic languages that makes explicit interfaces more than a little awkward is that dynamic languages can often respond to messages (err, “method calls”) that they don't know about beforehand, even doing things like creating methods on the fly. The only real way to know whether an object will respond to a message correctly is by sending it the message. That's OK, because dynamic languages consider it better to be able to support that sort of thing rather than static type checking; an object is considered to be usable in a particular protocol because it is “known” to be able to participate in that protocol (e.g., by virtue of being given by another message).
Why don't we require interfaces in dynamic languages?