Most people just call it saying "good morning" and don't think anything to it but to me its a deliberate intrusion into my world, demanding that I give them attention and respond in kind.
Well, most of the time I don't want to respond in kind. Usually because in kind makes no sense - if the person says "good morning" then that's a presumptuous statement assuming that my morning has been good so far (generally they are crap as I'm really not a morning person and really struggle with executive functioning fails in the first few hours awake!), alternatively the greeting is simply "morning" which is a statement of fact and not one I need telling, I'm perfectly aware that it's the morning that's why I'm out of bed! Of course then there's always the people that go even further and ask "how are you" or enquire as to your previous evening/weekend, requiring further effort to actually select an appropriate answer from the bank and verbalise it without resorting to sarcastic bites or scowls.
I fail at this a lot. My answers to "how are you" are often brutally honest and my retorts to queries about my night can cause awkwardness and uncomfortable reactions.
Not that I care, don't ask such a stupid question if you don't want to deal with my genuine response! I find questions about last night/my weekend to be intrusive and not always work appropriate, the worst of which is asking someone if they slept well - particularly if the person is known to be dating/in a relationship - what exactly is being asked?!
The nuances of social interactions can be lost on me, I fully acknowledge this and I work hard to ensure that I learn and maintain key skills for interacting with strangers, colleagues and friends (family have known me far too long to be bothered by morning-me!)
I just wish I could get people to understand the cost of this ridiculous ritual they engage in every day, how I have to use energy to recognise that I am being talked to, put on pause the thoughts I was having when interrpted, school my features into an appropriate 'responding' expression and engage my vocalisation skills while looking at the person and taking off my coat/signing in the building etc. Because you have to be doing something as you respond, if you stop still then this is taken as a cue for further conversation!
There is no answer, no way to stop people doing these silly social dances they insist on, I just have to keep going, keep doing what I do to cope and make it through the day without snapping at anyone . . . . out loud that is!