There is also an alternative explanation (which does not contradict this one) and is based on opportunity costs & networks. #EconTwitter 1/3https://twitter.com/econnaturalist/status/1154407122538569729 …
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Also (just realizing this now), I don’t see how this applies even in the one-way case. E.g. when you fly from Atlanta (hub) to Honolulu (dest), don’t you have to compensate the airline for their missed opportunity to sell someone a London→Atlanta→Honolulu ticket?