You share the same space. How distant are you with other people that you can't just say hi? Does it matter if you don't discuss politics after it?
When i was a kid, i had to take the bus and i forgot my bus ticket (a pupil, on one bus stop, everyday, the same bus stop the same bus driver on a school route...) and he put a lot of energy into telling me off.
A few days/weeks later i thought about it and i also thought about why i'm not greeting my bus driver when i enter. I started to say hi. I liked it. I liked saying hi to my bus driver.
I forgot my bus ticket again. No issues no worries. there was mutual respect and that mutual respect came to acknowleding him.
I like greeting my neigbhours as well. Somehow it makes a small connection between us.
and yes i read the part with the shield: The first step is a hi. Every other step is easier not harder. Finding out their names, a little bit of talking about family and friends etc.
If i would have worked close enough to Bill Gates i probably would have talked to him sooner or later. Why not? He is a human, not like Mark Zuckerburg.