No. Nothing you have said helped all that much. The answer is that it's either a bug or a poorly implemented feature depending on what Mac you have. And that's okay. People shouldn't expect so much from something still under development. It's the best thing or I wouldn't be using it. Mic drop.
My education had to start here though. I did not understand how OS X scales the GUI elements for higher resolutions. I assumed the resolution was picked from one screen. But the slider panel "larger text to more space" was for setting the GUI scaling resolution. But this is not the case. The (retina?) slider, selects a predetermined set of resolution and % of GUI size scaling up or down. It's a combo slider. Not unlike shifting gears.
The reasons why you may or may not get the slider depend on a variety of things. And I know some of them are good reasons. And for the others you can point to reasonable technical explanations why this is. But for most customers I can think of for Macs, it's not going to be believed that the Mac they resize text and graphics on all day...can't resize text and graphics? It's immaterial what the technical reason is. The technical reason is the detailed explanation of the bug, not the feature.
But even when you do get the slider it's a rudimentary implementation of scaling when compared to other offerings. And that can't be unnoticed by graphics professionals. Actually it probably doesn't go unnoticed in the dorm room with parents comparing the two most popular offerings. I might not mind. It's a fun puzzle to solve. But it's the consumer that might not want to edit some "wackidy file" that is undoubtedly in my future.
