I’ve always enjoyed watching people in public, overhearing snatches of conversation, noticing body language and movement. It comes from being a writer and trying to learn how people act and react, how they talk and move and interact. It helps me to make my characters more real.
During lockdown, I wasn’t getting that immersion, so I found an alternative. I live on a fairly busy, two-lane road, near an intersection. So when the traffic light turns red throughout the day, cars can back up past my driveway. This allows me to see the drivers in their vehicles as they wait for the light to turn green.
I find it fascinating to watch them for the minute or two they’re stuck there. Some sing along with whatever is playing on their car stereos. Others talk on their phones, either holding them up to their face or using the speaker (so it looks like they’re talking to themselves – which may occasionally be the case).
A few look around, maybe admiring the live oaks that line the road (it’s a canopy road), looking at the houses, the birds, and squirrels. We have a lot of wildlife in my area due to the natural setting. Red-tailed hawks are often circling overhead, along with the massive turkey vultures. I once saw a driver startled by the shadow of one of these birds as it flittered across the hood of their car. 
Then a few other drivers simply sit and stare. I wonder if they’re listening to music or a podcast, or if they’re lost in their own thoughts. I then try to imagine what they might be thinking about. Their day at the office? What they have waiting for them when they get home? Plans for the weekend? How they’re going to break off a relationship?
An infinite number of possibilities.
They never see me and never know what world I’ve created for them. That’s probably for the best. I doubt my imaginings are anywhere close to reality.
I’ve also done this while I’ve been stuck in traffic, looking around at the other drivers around me. However, it has to be done casually – no staring – because they can see me, too. It’s not as much fun, though. Sitting at my living room window, unseen by the drivers on the road, appeals to my writing self. It’s like looking at a scene in a story, a character enters stage right, and I quickly take them in and create a backstory. 
I find it good exercise for my imagination. I build characters from the people I see sitting out there for a minute. They move on when the light turns green, never to be seen again, but their snippet of story remains in my head, filed away for future reference.
RB