This is the intended behaviour. See the docs here: https://docs.python.org/3/reference/datamodel.html#object.__ror__

> These functions are only called if the left operand does not support the corresponding operation and the operands are of different types.

There's a further explanation in a footnote:

> For operands of the same type, it is assumed that if the non-reflected method – such as __add__() – fails then the overall operation is not supported, which is why the reflected method is not called.