It is possible the staff just didn't know about the break in journey rule, I was too tired to fight it at the time.
TIL, thanks!
On a related note, I found out the hard way that (some?) airlines don’t let you use a return flight if you missed the outbound leg.
Pretty bad really, I guess an example of where the theory of balancing the numbers doesn't match up with the reality that is obscene that they can gouge you for less service, I think it should ultimately be "admin overhead" + "flight(s)". Most people accept that a single can't always be half of a return but it should always be noticeably cheaper.
I have, on rare occasions, not shown up for the return flight because just buying a new one-way ticket for a new date/time was cheaper than rescheduling the existing return leg. I don't think you're actually supposed to do that either.
No. Many return fares explicitly allow a break of journey - especially non-advance fares.
It is the introduction of single-only fares which will have a greater impact than mobile fares.