Would you the agree that the difference between the 1" example and the 10 foot example comes down to whether the area below the vertical position below the disc constitutes a separate playing surface?
It's my contention that the issue in the rules highlighted by the example given by the OP is that there isn't a solid definition of what constitutes a separate playing surface. Nor is it explicitly stated that a disc the position of the disc at rest indicates one and only one playing surface that must then be played from.
Furthermore, I think the nomenclature of multiple playing surfaces is less helpful than it could be. My example earlier was that one could form a continuous line of discs, each one touching another at an edge, and travel from one playing surface to another, and yet at no point would any of the discs be touching or on two of the playing surfaces, nor would any two discs that were touching be on different playing surfaces. This then causes further confusion about the idea of stacked playing surfaces, and what delineates them.
I personally think that the OP example is two different playing surfaces by the spirit of the rules. (Although, any course designer or TD might be well advised to declare that an area of free relief, if I'm understanding the picture correctly). But, in any case, I don't understand where in the rules, as written, one makes the distinction.
As a further thought example, imagine the same scenario, but it's a rocky cliff wall that is straight up and down, with no ability to take a stance behind the disc if it is down low. Now imagine two different resting places, (A) one at the base of the cliff, touching it, and (B) the other vertically above it resting on the top of the cliff, but hanging over far enough that the front edge of the disc would allow a foot to be placed behind a mini if marked vertically below it. The basket is on the lower surface, so the cliff face is behind the basket.
If in position A, can I legally take a stance on top of the cliff? If in position B, can I legally mark on the lower ground? Why or why not?