Stragglers generally refer to people who aimlessly go to places to either live there, they think they are protecting something, or because they feel like they are mutually bonding with strangers/people by sitting in their cars outside of business/apartments/forest/parks.
Common examples would be mall dwellers, forest dwellers (people who live/squat in their cars
in the woods), "Van lifers," people who solicit businesses/people with no intent of purchasing, people who live in the Walmart parking lots, and squatters.