https://www.bbc.com/worklife/article/20190226-the-travel-tri...
The Saturday night stay rule is alive and well in certain markets. Business travellers like to be safely back home before the weekend, and their [employer's] pockets are deeper than leisure travellers.
Especially if you are doing like a two day trip that looks like it might be business. E.g. LHR to JFK Mon to Wednesday.
They tend to tier things so business travelers will pay more, so there may be fare rules that increase the cost dramatically the closer you get to departure date, or charge more if you do not stay a certain number of days (I've heard one week as well as requiring a 'Saturday stayover')
Of course business travelers are the ones most likely to research and plan out how to get around these, so they might book overlapping tickets pointing opposite directions and interleave them. Airlines get upset about this, but they also know that if they try to crack down that these travelers will just take their (substantial) business elsewhere.
You'd book from your home airport --> your destination --> Tiny Airport X, then skip the second flight, because the price would often be much cheaper that way.
Called "skiplagging": https://www.bbc.com/worklife/article/20190226-the-travel-tri...
I booked a one way ticket on another to make it work, then was surprised when I tried to return home that I no longer had a valid ticket for the first.
Of course, they'll helpfully offer to let you buy a one-way ticket at the counter, 90 minutes before departure, at maximal pricing.
He would have gladly skipped the first 2 legs of the trip.
Let's say you want to fly from Vegas to New york, it might be cheaper to buy SFO to new york, and hop on the Vegas->Mew York leg. They essentially make this option less viable, and can price each market differently.
But if it’s just A-B and B-A and you don’t take the return flight, no one cares. (I’ve even gotten flack for notifying the airline as a courtesy…)
E.g. LAX-NRT on 3/2 on UA 32 is $966 right now. Add a return flight on 3/9 and the flight _drops_ to $893.
I'd be surprised any airline gave you flak for telling them you were missing a segment. They might try to charge you more (!).
They do indeed, including trip change fees. For myself, I luckily got an agent who was nice enough to ignore what I had told her.
Full disclosure: I have a bit of a history of flying on what some call "mistake fares". Back in 2013 I flew "from Europe to Hong Kong and back", except it was routed via Australia(!) both on the inbound and the outbound. Was convinced I was going to be denied boarding at every single stop on the itinerary ...
I was also younger and fitter then :)
If you miss a flight and the airline determines you booked it (typically as a return or hidden city leg) without ever intending to fly it, they will very definitely try to make life difficult for you.
Try short-checking a bag to LON on a NYC-LON-Europe booking with AA or BA, they will refuse. They're worried you booked to Europe for a lower price but intended all along to leave in LON.
There are ways round this "rule", too. If you know what you're doing.
https://www.southwest.com/help/changes-and-cancellations/ove...
https://www.jetblue.com/legal/notices-to-customers
However, this isn't a guarantee you won't get bumped. This just means that the maximum number of tickets sold to customers equals the number of seats on the plane. If the plane changes, so do the number of available seats. And not all passengers are customers. Some may be crew deadheading to another location.
More generally, it is less common for low cost carriers to overbook flights because their passengers tend to be cost-conscious vacationers who paid for the flight out of their own pocket and aren't about to forfeit the fare. Usually these passengers show up at a very high rate. So there usually isn't even a reason to want to overbook these flights.
For the return leg, you check in online, download your boarding pass, and ignore it.
You "had a flat tyre on the way to the airport", or similar. In these situations, telling the truth doesn't help.
Late last year I flew aaa-bbb-aaa-bbb-ccc-ddd across Europe, all in one day, for exactly that reason. Five flights across four separate bookings/tickets. The connection at ccc was the tricky bit, not only "connecting" on a different ticket (so not really a connection), but a different airline alliance.
They design the system, you follow the rules. Unintended consequences aren't really your problem.