I find it so charming that people from the first world just assume that unplanned trips are the norm, and coming back as per expectation is can sometimes be surprising (even if it's a very long trip).

Do take a look at what people from developing countries go through - sometimes you cannot even get a visa without all your lodging booked and a confirmed return flight ticket.

Or you are accepted to go to a conference in the USA to present your research and the USA conveniently grants your visa for you one week after the conference occurs.