Maybe very large aircraft do actually necessitate a much higher number of pilots thinking about overnight stays and being out-of-hours, deadhead etc.
Sami's explained this a number of times. You get screwed if you, say, use A300s for purely domestic service. But that's just the way it works for now. It assumes certain types of aircraft, based on size, are used in certain types of service that necessitate much higher pilot counts.
Interesting numbers about BA. Anyway 13 per aircraft still seems to high.
No way. In fact, I could argue that's actually a litte low.
You'll need at least 9 pilots just to fly an aircraft over a 24-hour span (for planes requiring 3 pilots at a time), and that only covers 5 days per week. Then you need another
set of 9 pilots to fly the other 2 days. And you're not going to just hire them 2 days per week, so you've got them onboard all the time, and they'll also cover time off, so you end up having 6 full "sets" of crew. And that's at the very least.
36 is undoubtedly too high, but it was done (as many things are in AWS) as a means of, overall, averaging out when looking at an entire fleet of your average airline as well as average routes. If you fly just Large aircraft and just short-range you're getting a bit screwed with the formula, yes. But considering the margins allowed by those aircraft in-game, giving up a bit too much in salary is no big deal.