It depends a lot on the person being interrupted. I tend to get into conversations with people wherever I go. And I'm frequently not the one who starts the conversation. I've had a handful of people ask me about my JBL (most ask if it's a Kindle
) and it doesn't bother me. Most are just asking a quick question and I can sense when a quick answer is all that is needed.
People are used to seeing people with newpapers and laptops. E-book readers are still fairly new to most people. I'm guessing, even though you probably "send out vibes" that would otherwise discourage people from bothering you, their curiosity overcomes that.
Desert Grandma is right about there being no private space in public (at least it's true in ost of the USA). You may just have to accept that's the way it is and deal with it.