This is a wild projection of your own experience onto someone else's actions.
> If you really want to read a book in peace, try a library.
I've quite enjoyed the times I've taken a book to a restaurant and read over a meal. I do not appreciate you, or people like you, dictating how I ought to act in public in a way that doesn't affect anyone else in the slightest.
I don't want to start conversations when I'm alone at a table with my book. The fact that you find it somehow less social for me to be on my phone instead of reading a book when I am minding my own business at my own table seems like a tremendous failure in your own boundaries and expectations of other people.
I asked a friend who doesn't use a smartphone about how it feels walking into a room full of people with phones and he told me the same thing. I have a smartphone but I don't take it out reflexively. I don't even consider myself a very social person or an extrovert, yet it always has to be ME to start a conversation in a room full of people because they would rather stare at a screen that say a hello.
I'm going to talk to you whether you like it not. If you don't want to talk to people, then maybe don't put yourself in a social setting? Imagine entering a coffee shop and finding it dead silent. I would just go home and make some food. If you have a problem with me talking to you, go ahead tell me how much you don't appreciate it or whatever, I don't care.
Do you make a habit of interrupting people who are reading? If so I can just about guarantee that you're "that guy" to the people you're doing that to.