>really it's the behaviour of the two cases taken together that can seem inconsistent.
Why do you think so? I think that both cases seem consistent, or rather, correct (and therefore this example should not be treated as a common Python mistake), because x is not assigned a value anywhere in class C, and C inherits from A, so it should be clear to anyone knowing OOP and inheritance, that C's x is the same as A's x. (And the same holds true for inherited methods.) Even the OP says that in the post:
>In other words, C doesn’t have its own x property, independent of A.
Why do you think so? I think that both cases seem consistent, or rather, correct (and therefore this example should not be treated as a common Python mistake), because x is not assigned a value anywhere in class C, and C inherits from A, so it should be clear to anyone knowing OOP and inheritance, that C's x is the same as A's x. (And the same holds true for inherited methods.) Even the OP says that in the post:
>In other words, C doesn’t have its own x property, independent of A.