A lot of the comment here is simply demonstrating hindsight is twenty twenty/ it’s easy to be wise after the event.
Looking specifically at Brits the Australia/New Zealand Many backpackers, retirees, those able to take long breaks who are now caught up in this probably travelled out well over a month ago, quite possibly two or more.
Looking back at where I was just six weeks ago whilst some of the places en-route to the likes of Australia may have had local restrictions but the flights were operating normally and were pretty full. Very little was being said certainly officially, in either Australia or the U.K. about the consequences of the contagion really ramping up outside Asia (even though we are well aware now that it was already starting).
AFAIK It was only about four weeks ago that some european airlines began to change schedules, cut flights..still no major thoughts/announcements about Aus/NZ having major problems as I recall it but capacity had started to be taken out of the networks that serve that part of the world.....ticket prices started to go up..
So the question some people were asking themselves was should they cut short their holiday down under when nobody was shouting “fire” locally or in the U.K. (i.e. the FCO). It was going to cost thousands to get new tickets home and the insurers would not pay out.
I think may people were possibly getting uneasy but assumed since they had paid for travel insurance and the mood music from home was just wash your hands whilst singing happy birthday that all would be OK.
Couple of weeks back, or even less, finally the restrictions kick in, in some places very rapidly with very little warning...the FCO finally wakes up...by which time more airlines have cut back and there’s even less capacity to get people out.
Having been involved in one flight bringing people back from the Far East and having heard some stories many of those stranded weren’t feckless, were not daft, they got caught out by the lack of urgency being displayed by one government and the very fast changing restrictions put in place by others.