I have also noticed the reaction some people give when you strike up a friendly conversation by asking how their day has been. I see it most with shop assistents and cashiers.
Usually they would ask "How's your day going?" as they get to work at scanning your items etc. But they surpirsed look they give when you return the question and actually listen to what they have to say is amusing.
I guess a lot of people are too caught up in their day to enjoy a few minutes of small talk with a stranger - as you alluded to in your closing paragraph.
Thanks for sharing this post Ben, it's good to know other people lke to spread some positivity as they go about their day 😊.