Compression is just the discarding of irrelevant or less relevant information. With images or video, that means keeping the perceptually meaningful content and discarding the rest. An improvement might come about if the encoder was removing irrelevant variations (noise), or smoothing out unnecessary details away from perceptually salient objects (making them easier to see).

It's pretty hard to make an image encoder that maintains the important perceptual qualities of every possible image, so IF their encoder is good, maybe they just didn't test it on the whole range of stuff they eventually used it on.

I sort of agree. I think it's "legendary customer satisfaction" that TFA is thinking of (that's where Apple has always lead, anyway). If you have a Mac you may have the same lowish rate of problems (many of which are possibly component problems and not much to do with Apple), but statistically speaking you're more satisfied overall, which is probably driven by the large fraction *without* problems.

The conclusion that a train may be "less green" than a plane is somewhat dependent on what you look at. The article notes that this is because the particular train they looked at, the Green Line in Boston, uses local power that is being generated from carbon-emitting sources. Actually, even that is only part of the story... you can read the original research (http://www.iop.org/EJ/article/1748-9326/4/2/024008/erl9_2_024008.html) if you have some kind of institutional subscription to Environmental Research Letters. It shows that the energy use is actually lower or the train, and that another train (SF muni) does beat the "large aircraft" (the small aircraft is much worse).