The coatings, which do matter quite a bit when you are optimising for some durability/optical quality tradeoff.
Glass covers make screens more durable, but imply internal and external reflections. Laminated screens on glass panes solves the internal reflections and improve transmission, but do not help with glare and external reflections. Those can be improved by texturing the glass, but at the cost of diffraction and smearing, leading to a decrease in effective resolution. Unless the texture becomes small enough, but then you need it to be durable enough to avoid being wiped or damaged by things that might come into contact with the screen.
It turns out that there is a lot more than the bottom layers that matter in a display. You can see all these problems being solved in succession when looking at the evolution of Apple’s displays over the years (and others’, but it is much easier to find information about the good and bad sides of any Apple product). It’s fascinating, actually.
[edit] add the issue of oils on the human skin and you have do deal with oleophobic coatings for touch screens, which is another very important factor to consider. In addition to how the touch sensors are integrated.
> What exactly are they "engineering" here?
The coatings, which do matter quite a bit when you are optimising for some durability/optical quality tradeoff.
Glass covers make screens more durable, but imply internal and external reflections. Laminated screens on glass panes solves the internal reflections and improve transmission, but do not help with glare and external reflections. Those can be improved by texturing the glass, but at the cost of diffraction and smearing, leading to a decrease in effective resolution. Unless the texture becomes small enough, but then you need it to be durable enough to avoid being wiped or damaged by things that might come into contact with the screen.
It turns out that there is a lot more than the bottom layers that matter in a display. You can see all these problems being solved in succession when looking at the evolution of Apple’s displays over the years (and others’, but it is much easier to find information about the good and bad sides of any Apple product). It’s fascinating, actually.
[edit] add the issue of oils on the human skin and you have do deal with oleophobic coatings for touch screens, which is another very important factor to consider. In addition to how the touch sensors are integrated.