Or is it friends and family like how 70% of auto crashes happen within 10 miles of home simply because that's where you drive most often?

I think this might be correct, especially during a lockdown, those are the people most people see.

Whether you get infected or not is a game of chance. There are a lot of factors affecting the probability:

* Being indoors during contact (increases)

* Duration of contact (every minute increases)

* Physical distance between contacts (every meter decreases)

* Amount of contacts (every person increases)

* Wearing masks (decreases)

* Washing hands (decreases)

* Coughing, speaking, singing during contacts (increases)

Meeting people close to you ticks basically every probability-increasing checkbox in the list.

Don't forget presence of pre-existant antibodies in the person. (decreases)