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.
Every additional complaints about my life or happenings in my life that I would have would be unrelatable to the maids and the drivers at our house and it might make them feel uncomfortable.
No interest in learning who they are? What they like? When they have birthday?
If you have a bad day, for whatever reason, you think they couldn't relate to having a bad day?
They couldn't relate - my bad day would be related to losing a few points on a foreign exam or if my favorite restaurant was overbooked.
They shouldn't have to share our burden in addition to the work they are doing and potentially feel bad.
I'm not going to post my credentials on HN but I have it on good authority that these jobs suck enough without having to pretend to relate to your customer. Hello is fine but beyond that and the janitor probably has their shields up lest they say something stupid the same way a white collar professional would be very careful talking to Bill Gates.