Earlier quoted context omitted.
And they're paying into the library too with their taxes, poor or not.
They may or may not, but I would put money on a majority of them not paying income tax due to the large number of homeless and vagrants. But that is beside the point. Paying taxes does not give you the right to a) break the rules (surfing porn IS against the rules) and b) causes an environment that is not conducive to the intended use (i.e. a filthy environment that drives away legitimate users)
Is it just the vagrants watching porn that pisses you off? That's maybe caring too much about the topic, but it raises a fair point.