Just looking up some travel insurance quotes and my mind wandered.
So you are on a flight and it gets diverted. You then land in a country that is not on your insurance declaration. Or you are transiting through an airport and you get ill and need to be admitted to a local hospital.
Are you insured for that country?
I know it's unlikely - but planes do get diverted, people do end up in countries they hadn't planned to and people do get ill in transit.
I had a look at my policy I have - and it says you don't need to declare a country if you are stopping over for less than 12 hours and you aren't leaving the airport.
It doesn't say what happens in other unforeseen circumstances.
And some countries have very expensive medical costs