[ealgeone]

Think about how many people travel by air.

For the US:

44,000 daily flights (avg)

5,000 planes in the air at any one time.

https://www.faa.gov/air_traffic/by_the_numbers/

Average daily passengers in the US (2018): 2,789,971

******

That's a lot of people bouncing around and coming into contact with others.

Now consider those working at the airports.

Taxi/limo drivers.

All those 2,789,971 people leave the airports and come into contact with even more folks.

[polymuser]

Just think of the close breath proximities boarding and riding in the closed-cabin planes.