The reason Hungarian notation conveying type ("systems Hungarian") is frowned upon in Python is simple. It's misleading. A variable might be called iPhones (the integer number of phones, maybe :-) but because it's Python, there's nothing at all to keep you from putting something other than an integer into it! And maybe you will find you need to do that for some reason. And then all the code that uses it is very misleading to someone trying to understand it, unless of course you globally change the name of the variable.
This notation was intended to help you keep track of variable types in statically-typed languages and was arguably useful for a time. But it's obsolete now, even for statically typed languages, given the availability of IDEs that do the job in a much better way.
