I do it... and I can remember my mother gently tolerating it when I was a kid. (Actually I can remember her doing it too. I remember me and my mom and my brother all eating together and reading our books, and occasionally looking up to share what we were reading about.) DH and I have always read at the table, too. I only have one out of my three (DD1-- she's 5) who can read independently, and I let her read at the table if she wants to.
I come from a long line of bibliophiles, and it's just what works for us. To me, there are WAY bigger fish to fry, and I'm not willing to give it up myself, so I can't prohibit my kids from doing it.
Our rules are:
1. We don't read at the table when there's a guest.
2. If a person is so absorbed in their book that they don't notice when they've been spoken to, and don't look up to answer, then that book is probably too absorbing for the table, and should be put away. I give one chance on this one, and if you're rude a second time, I ask you to either put the book away, or go in the kitchen and sit there and eat with your book.
Reading while walking I would allow unless there was a clear and present danger to the child's life. Heck, I used to prop a book on top of the double stroller, and put the twins in there, and push them up and down the street while they napped and I read and read and read.
Maybe we are this way because I have a tendency to read at the table when there is no reason not to. No one really seems to have a problem putting the books away for whole family meals or guests, so I don't worry about it.
At least I don't have to worry about anyone reading and driving. Both of my girls get motion sick and throw up if they read in the car.