Interesting that when I worked a wee while for a pharmacy doing the odd delivery, I was asked not to say "how are you" to the customer. Not a rudeness thing, but common sense, as if they said "oh, my back's a bit sore" as then they might be expecting a response which I would be unqualified to give. Just think if I said "you need a rub for that" and it was wrong/they were allergic to rub etc.
So it was just a bland "hello there *name*" and if they said there was anything wrong the stock answer was "love to help but best if you ring or visit the pharmacy or the doctors".
Did once call on an elderly lady who was on the floor - so rang 999. I should have rung careline as they provide specialist care in that situation, but I didn't know she was with careline, not something I was expected to know.