I'm British, living in Australia since 1968, with an accent to match.
On a recent 14 day trip to Saigon (Vietnam), Bamboo's Melbourne staff didn't want to let me board because I didn't have a visa - Australians require visas to enter Vietnam, Brits may enter for up to 15 days without a visa.
And, you guessed it, 14 days later their staff in Saigon didn't want to let me board to return to Melbourne, because the Australian government, in its brilliance, no longer provides any physical visa or passport stamp for permanent resident holders, so I had no physical evidence of a right to enter Australia.
Fortunately I had spotted both these potential problems beforehand and carried printouts from the Vietnamese government website and of the email confirming my resident's visa, along with reams of other printouts about CPAP machines, batteries, etc, which I didn't need to produce. It shouldn't be necessary to spot and per-emptively patch the holes in the system before you fall into them, but it's well worth trying to spot them ahead of time.