As an American who spent a year as a visiting researcher inside Russia's Foreign Ministry, I can confirm that these differences in decorum are very real. They

As an American who spent a year as a visiting researcher inside Russia's Foreign Ministry, I can confirm that these differences in decorum are very real. They are common knowledge in Russian society, and Russian diplomats are trained to take them into account when emulating Western social graces. Broadly speaking, in my experience Russians conceive of smiling as something precious, to be shared with friends or family, not wasted on strangers crossing your path. However, if you have occasion to interact with someone (e.g., asking for directions), they may smile, particularly if something about the conversation generates a feeling of closeness. I got a lot of smiles and handshakes in Moscow from strangers when they found out I was studying at MGIMO, since they (incorrectly) assumed it meant I'd snubbed Harvard or Yale.