Considering the homeless people that I don't kick out of my library despite the many bags of mysterious personal effects, the odor caused by of lack of access to soap and water, and the general air of decrepitude, I'm not sure you can argue that there is such a thing as too poor to use the library. And you can't look at anyone and predict whether or not they're able to use the internet, trust me. The only privileges invoked here are literacy and a body which works sufficiently well to operate the machine.