This comic barely exaggerates how easily your character gets given important assignments from the military of a government they're not even a citizen of.

The in-game government being referred to here is known as the New California Republic (NCR), and they have limited control of select areas of the region your character is in. Most of the area is independent settlements, and it's made pretty clear that your character is not a citizen the NCR.

Granted, the game has a faction reputation system, and you have to be BFFs with them to do some things, but  all things considered, they are rather trusting of you,.