Greetings and farewells are the foundations of social intercourse. Like real foundations, if you get them wrong the whole structure is likely to collapse in an embarrassing heap. Unlike foundations you can't just do them once and then forget about them; there are opportunities to get them horribly wrong multiple times every day. Superficially, English and Polish greetings and farewells look similar: there is cheek kissing and handshaking in both. If I was in Japan or the Canadian Arctic and had to deal with unfamiliar things like bowing and nose-rubbing, I would probably pay more attention and get it wrong less often.