This article summarizes some different case studies and scenarios: https://www.erinbromage.com/post/the-risks-know-them-avoid-t...
I got to toilette hypothesis, so don't know if the rest had data. That said, this still sounded like speculation. Are the rest more backed with data?
Surfaces play a significant but minor role, outside exposure (a lot of air) is almost irrelevant as long as people don't stay long close to each other.