I wonder if any Russians can weigh in if this still feels accurate. I'm familiar with Polish Culture, which is less fun, frivolous, and happy than American culture, but a smile is certainly not an attack, just reserved for genuine occasions. Service people are in no way expected to smile unless there is some honest reason to.
I am Polish and I can not confirm that. I felt a sharp decline in "smiles" after my move to Germany where your description fits much more. I see much more people smiling for no obvious reasons when I visit Poland from time to time. Something which is not perceived as something else but friendliness by my German SO though while I've witnessed Germans being perceived as very cold by US Americans for the way they are. I…
Also, service people are not supposed to be fake smiling, we are actually expecting their emotional labor on top of the labor of their job. They are supposed to be cheering us up with their genuinely good attitude and "changing someone's day for the better" with their smile. It's all pretty exhausting.