Interesting question [but not for the reason originally asked]!

Many years ago I flew to Barbados to re-board a cruise ship [it was a
world cruise -- originally sailing from NYC -- and I had to return home
for a few weeks during the period of the voyage ... and then re-join the
vessel and my cabin -- and my clothing that I left aboard -- in
Barbados].

I arrived in Barbados from NYC via a one-way air ticket [the ship was
going back to NYC] ... and had my cruise ship room key [no ticket as I
was re-boarding and theoretically in-transit] ... and discovered that I
was not allowed into Barbados without proof of a departure ticket.

After much arguing, and showing my credit cards, it was permitted by the
Barbadian authorities that I be escorted through immigration/customs to
the departure area ... where I had to purchase an actual one-way air
ticket to NYC and immediately show it to the accompanying
immigration/customs people .., who then let me officially enter ... and
I subsequently turned around at the airline counter to redeem the air
ticket.

Ergo: Be careful if you try to enter any foreign country without proof
of departure (e.g., a cruise ticket or proof thereof, an airline ticket
or proof thereof).

There is no intelligent answer to bureaucracy [but I do understand that
Barbados just wanted to ensure that anyone arriving would be leaving]!