Greetings and Salutations

Yesterday morning in the shower I was thinking, probably about something shower related like shampoo or washcloths, and had one of those stream of consciousness things where you start at one thing and end up at something completely different and it makes sense to you at the time, but you can't really explain it to yourself later, and certainly couldn't explain it to anyone else. The thing that I ended up at from shampoo, or whatever it was that began it all, was the difference between the phrases "Good morning" and "Good afternoon." Have you ever noticed (or maybe it's just me) that saying "Good afternoon" seems way more formal than saying "Good morning?" It is perfectly acceptable to wish someone a good morning without seeming overly formal or cold, but wishing someone a good afternoon just seems awkward in everyday conversation. The only times I have ever actually spoken the words "Good afternoon" they were closely followed by "Vincent's. Can I help you?" or "Century Bank." Why is it that switching the word "morning" for "afternoon" suddenly makes a phrase something you only say when answering the phone at your place of employment? Or am I just crazy and people wish each other good afternoons without formality all the time?