Given a travel related situation, and given a specific question about the situation, summarize the question into a title

[Q]: In the last four days I've driven my motorbike from Milano to Kalamata going through a few nations on the east side of Adriatic sea, and in a couple of occasions I found myself crossing two customs to enter or exit a country (in both cases it was night, and cold, and I was freezing, and after driving for hours and hours, so I did not take note of which border...but probably entering Montenegro and exiting Albania)

Why is that? I noticed that in all occasions one custom asked for both my passport and my bike documents and the other custom asked for just my passport, but still it doesn't make much sense.

[A]: Why two customs/immigration controls?


[Q]: I see on Wikipedia that both Vietnam and Philippines honor an IDP. However I cannot find specific information on whether my motorcycle license would translate and allow me to rent and drive motorcycles in the two countries. Will an IDP allow me to do so?

[A]: Will my US motorcycle license translate via International Driving Permit in Vietnam and Philippines?


[Q]: I have an ESTA for the US, valid until Mar 20, 2020. I have confirmed the ESTA is still valid on the U.S. Customs and Border Protection site. However, the airline I have a flight booked with will not allow me to check in online due to not having a valid ESTA/VISA/etc.

Does this mean I'm not going to be allowed on the flight or is it simply a problem with the online check-in? And if I'm allowed on the flight, should I expect issues on arrival in the US?

[A]:
Valid ESTA for US, but not allowed to check-in Online