According to https://docs.python.org/3.8/library/shutil.html#shutil.move

"If the destination already exists but is not a directory, it may be overwritten depending on os.rename() semantics."

I interpret "depending on os.rename() semantics" to mean it will follow os.rename()'s behavior.

According to https://docs.python.org/3/library/os.html#os.rename

"On Windows, if dst exists a FileExistsError is always raised."

However, their behaviors are not the same.

For os.rename, it does raise FileExistsError if dst exists.
For shutil.move, it silently overwrites dst.

It's either a bug in behavior of shutil.move, or the documentation need to be updated.