Summary: https://www.consumerreports.org/consumerist/all-major-u-s-ai...
Full text here: http://www.dot.gov/sites/dot.gov/files/docs/Notice_24hour_ho...
European airlines have different policies regarding cancellations, often based on the type of fare you select. Sometimes you get a full refund, other times only the taxes and fees.
Edit: I should add that I don't know if this specifically applies to Kayak, etc. I'm not sure if that's what you were specifically looking for.
AFAIK, only if you book with an airline direct.
After he realized he made a mistake he sought out the airline staff and they told him he had to go to some website which showed that he had checked in, but not the extra charge or option. Eventually he made his way to a service desk at the airport and they told him to call a number after he landed on the other side.
The "customer service" representative then informed him that since he had already taken the flight, he couldn't get a refund.
I helped him file a complaint with the airline explaining the English and the lack of help from airline staff and the confusing remediation directions he received. They responded very quickly informing him that he would not be refunded but to please fly again with them.
My read is that he probably screwed up and could've asked more questions at the kiosk. In addition, you're a supportive BIL!
The kiosk was one of those touchscreen things so nobody to ask when he was making the mistake.
It is ultimately his mistake, but at the same time, they're keeping >$40 he accidentally spent so he could board an aircraft 3 minutes early. It's kind of silly.
Hotels and car rentals now have non-refundable rates, something that didn't exist 10 years ago. Many hotels add resort fees, extra service fees, charge $7 for a bottle of water, etc., that they never would have tried 10+ years ago. Airlines have long had non-refundable fares, but penalties have increased tremendously. Anecdote: a friend of mine booked a weekend trip in 2009, the return flight was Sunday 12:30 am. When I pointed out to her that was essentially Saturday night, she got on the phone to change her ticket to the last flight out that same Sunday. $40 change fee. Today that would almost surely be $100+ on any US-based airline.
All these extra fees aren't aimed at millennials specifically, but I sure don't see them resisting enough to have any of these companies reverse or reduce some of their fees in response to consumer complaints or dissatisfaction.