Julia, thanks for posting these!

Many years back, I had the misfortune of flying between Vancouver and Frankfurt on one of those Air Transat A330s where they squeeze in an extra seat in each row. I'm quite thin, and I paid extra for a bulkhead row for extra legroom, and it was still extremely painful. A colleague on the same flight had a neighbor who literally did not fit in his seat (as in, he could not squeeze his butt between the armrests). This neighbor then raised the armrest, spilled over onto my colleague, and smiled and thanked my colleague! My colleague is incredibly kind-hearted, generous, etc., and also quite thin, so he acquiesced.

The sad thing is that more and more airlines are jamming in more and more seats, even as people get larger. The cause is the classic mechanism of market failure due to asymmetric information: most passengers have no idea what kind of seats they'll get, so they don't figure this into their purchasing decisions. Therefore, airlines have no incentive to provide better seats. (A similar mechanism is why you tend to get uniformly crappy restaurants in tourist trap locales -- the tourists can't tell whether a restaurant is good or bad, so the bad ones can outcompete the good ones.)