You talk to an npc, they ask you to meet them at another location. They wander off wearing some old clothes and maybe a pistol. Meanwhile you barely get there wearing armor and an arsenal.

Does everyone have a super jet pack? A long run stealth boy? Are they taped into the Speed Force?

Inquiring minds want to know.

Jet. Either they or you are doing it. Jet explains all of life's mysteries. Or I suppose it could be psycho, you were really just staring at various objects having conversations with it, while the other guy wandered to the correct location.

Maybe, while you were luxuriating in your nice safe vault, the survivors above ground were learning how to stay alive, which should mean avoiding conflict.

Or, you know, the secret jetpack thing.

im pretty sure they all burrow through the ground to their destination.

seems like a good way to travel as long as you don't take the wrong turn at albuquerque

For some reason I imagine this requiring copious amounts of tape. I suppose that might explain why adhesive is always in short supply.