In English why is “Good Morning/Day/Afternoon/Evening” a greeting, but “Good Day/Night” a farewell?

Question

Told someone “Godd day” as a farewell after hearing someone tell me “Good day” as a greeting. This made start thinking why why wishing someone good fortunes depending on the time of day is either a greeting or a farewell.

I’ve never heard some tell me good morning as a farewell not telling me good night as a greeting.

In: Other

Answer 1

Depending on context and tone, each phrase is actually short form for a longer phrase.

Good day = it’s a good day today

Good day = have a good day

Good afternoon = it’s a good afternoon

Good night = have a good night

Something like that.

Another example:

See ya = I will see you later