For Python that is properly source controlled, audited and understood I do agree it isn't that hard to port. However unlike many more compiled languages there's probably a LOT of python code out there that isn't which makes changes to Python and its APIs more risky. Don't get me wrong - this is one of the reasons why the language is popular - it is seen as "easy and approachable"; you just write a script and it works for the most part. It also was often the only language built into many distro's other than bash making it ultra convenient.

Which means a lot of it written isn't catalogued, in source control, whatever but still doing stuff people need and often forgotten about. This makes changes of Python IMO more risky. I've seen Python scripts on old Linux images lurking in the wild working for even decades without people realizing they are there set up by non-dev's people back in the day. Another example would be some financial analyst coding a script to produce reports that are used to make decisions and need same behavior each time - one day the date time function maybe in this article will just stop working often with the original person who wrote it just to get stuff done quick long gone.

IMO migration from 2 to 3 was particularly painful for Python because of the way it/was is used, historically who the main users of it, its popularity (wide blast radius) and how it is often Python is updated by blanket system upgrades given it is standard on many machines. Being aware of what needs to be upgraded for a given large scale environment is most of the work.