High volumes of travelers siphoning through the same paths, touching the same surfaces, interacting with the same service personnel. Those travelers being from

High volumes of travelers siphoning through the same paths, touching the same surfaces, interacting with the same service personnel. Those travelers being from all-over, thus introducing new region-to-region microbiota mixes. Those travelers often tired or dehydrated from long plane travel across time-zones. Even a heavily-trafficked park, grocery store, or DMV-like public service outlet might not face the same volume of widely-exposed & weary people as an airport does.