The Japanese language has stock phrases that are always used in certain situations. Before you start eating a meal, you say “Itadakimasu” and when you’re done you say “Gochisosama deshita”. These phrases are so entrenched that Japanese people even say them when they’re by themselves and no one is around to hear them.
There are also stock phrases for when you leave and return home. When you go, you say “Ittekimasu!” (I’m leaving) and the whoever’s still at home says “Itterasshi” (Have a safe trip). Then when you come back you say “Tadaima” (I’m home) and whoever’s home says “Okaeri” (Welcome back).
I was surprised to hear from a Japanese friend who lives alone that she still says “Ittekimasu!” and “Tadaima”, even though there’s no one to hear her and offer the reply phrases. I couldn’t help but laugh, because imagining doing the same thing in English comes off as a little sad.