Although this is closed, I stumbled across it while looking to see if this behavior had changed at all recently, and I have a suggestion I think might work.

How about we take Tim's example error function which was added to the docs, and it's bound to something like shutil.REMOVE_WINDOWS_READONLY, so it can be used in the following way (probably with a better name):

shutil.rmtree("C:/readonlyfilesinhere", onerror=shutil.REMOVE_WINDOWS_READONLY)

Good idea? Too weird?