Sounds like she was surviving doing chores in exchange for a place to sleep (in two different countries). It's possible she didn't have a plane ticket lined up.
It's so expensive to not take a return ticket, I doubt she didn't had a return plane ticket. Maybe she moved her flight or missed it, but only rich people don't buy a return ticket.
I am not sure if the comment is serious or not. Often one way tix are not much more than half a round trip tix It used to be one way tickets were like 70+% of a round trip, not as much anymore
For international trips it's still the case, at least in my country?
She might even have done this on purpose to get a free ride home