Yeah, despite the hype, Apple doesn't pay /that/ much attention to this stuff: they mostly succeed at these design issues because their direct competition is ludicrously incompetent at it ;P. (Seriously: Android needs to hire a UX designer, although I will say that 3.x is getting much better.)
If you want a really awesome example, here's one that I noticed when I was first developing Cydia a few years ago, and had to do a lot of "iPhone-native CSS" (I am one of these people who stares at and slaves over individual pixels in designs) that I believe "cannot be unseen":
So, as stated in this document, cells are 44px "tall". However, this description doesn't take into consideration the effects of the borders: only one of the two borders can count for the spacing, as there are N+1 of them in a group, not N*2.
In this case, the top border is included in the 44px "rythm", but in either case, that means that the open area inside the cell "between the borders" is actually 43px, an odd number. Of course, the fact that it is odd is unimportant: you just have to be consistent.
This is why the height of the switch in that example is actually 27px: that way it will feel balanced. Meanwhile, the height of the right chevron disclosures is likewise odd: 13px. The slider control is a 9px bar with a 23px handle. Even the little speaker is 5px at its narrowest, and 23px at its widest.
Great, right? Only... now that we've been staring at this for so long, you might notice that the text looks imbalanced, because the cap height of the font Apple uses is 12px. This is also why I say the top border is included: the text is a half pixel higher than really feels right.
Of course, this is a subtle issue, and I'm certain that a pixel here or there is the kind of thing a normal person doesn't notice, but it slowly drives people like me /nuts/ (which led to a bunch of little tweaks--even requiring custom chevrons--in the CSS I use for mobile websites).
About the borders. I also noticed each cell is actually a space + 1 border. So you are right to say each table group is actually N+1. The extra pixel has to be subtracted from somewhere and I believe it's in the space between groups.
I haven't looked into the cap height issue as much as you do but one thing that really bothers me and as a result the developer I work with is that Helvetica and Helvetica Neue have different top and bottom boundaries. So there are slight differences in text render on the Retina display.
If you want a really awesome example, here's one that I noticed when I was first developing Cydia a few years ago, and had to do a lot of "iPhone-native CSS" (I am one of these people who stares at and slaves over individual pixels in designs) that I believe "cannot be unseen":
So, as stated in this document, cells are 44px "tall". However, this description doesn't take into consideration the effects of the borders: only one of the two borders can count for the spacing, as there are N+1 of them in a group, not N*2.
In this case, the top border is included in the 44px "rythm", but in either case, that means that the open area inside the cell "between the borders" is actually 43px, an odd number. Of course, the fact that it is odd is unimportant: you just have to be consistent.
This is why the height of the switch in that example is actually 27px: that way it will feel balanced. Meanwhile, the height of the right chevron disclosures is likewise odd: 13px. The slider control is a 9px bar with a 23px handle. Even the little speaker is 5px at its narrowest, and 23px at its widest.
Great, right? Only... now that we've been staring at this for so long, you might notice that the text looks imbalanced, because the cap height of the font Apple uses is 12px. This is also why I say the top border is included: the text is a half pixel higher than really feels right.
Of course, this is a subtle issue, and I'm certain that a pixel here or there is the kind of thing a normal person doesn't notice, but it slowly drives people like me /nuts/ (which led to a bunch of little tweaks--even requiring custom chevrons--in the CSS I use for mobile websites).