As an Elite Plus on TK, I am fully aware that TK has a lot of connecting traffic, that being said, this summer they will have appx. 2400 seats a day between IST and North America, vs. the 280 or so they had a decade ago. From my own experience I would posit that half of those are US-Turkey traffic, so about 1200 seats, vs a tiny fraction long ago. OTOH hand Delta has about 270 seats per day (depending what metal they fly this summer) the same essentially that they had a decade ago, and has lost a lot of the connecting traffic that they once had on the North America end. The market has grown hugely, and DL has left a lot of it on the table (down to getting bullied into the farthest gate at IST!).

FWAAA, not quite. TK HAD a terrible reputation for quality and not so great for safety. They have worked very hard over recent years on both counts, but these reputations do not go back THAT far. Regarding labour, while costs are less, they are not as cheap as they used to be especially as most TK pilots now come from the international market for example (although obviously FA's and ground personnel are somewhat cheaper). Also regarding EK, it is not that its straight costs are much cheaper laborwise, but rather that the tax and other liabilities are less.