Well, at least in NYC, I tend to narrowly avoid crashing into them on the sidewalk.

Perhaps it doesn't apply to you, but I don't think 90% of people who read books while walking are as good at navigating around obstacles as they think they are.

Used to do that too and from school after a while you learn to walk around obstacles without breaking your flow.

Got me an extra 40m reading time over the day.

I do this regularly when I walk around our neighborhood or to a nearby park. I usually make sure to hold the book up to help my posture, and look around frequently. Haven't ran into anyone yet, and often saw them before they looked up from their phone and saw me (most people, I've learned, don't walk on the proper side of the road). Allows me to get a lot more reading in, really, and helps me focus and digest what I'm reading a bit more when I want to.