It's not intrinsically difficult, but in Python it's arguably un-Pythonic and somewhat awkward. Like, sharing references has built-in syntax that's taught to most Python programmers within their first hour with the language, whereas copying - without writing a tedious manual implementation - requires importing the `copy` module [0], which outlines a number of pitfalls, quirks, and caveats with the process, and that I've literally never used so far as I can recall in a decade of professional Python development.

[0] https://docs.python.org/3/library/copy.html