Your standard Internet cafe also doesn't operate at taxpayer expense, so they don't particularly care if you h4x0r the m4tr|>< from their computers. All they want is your cold, hard, plastic.

Libraries, by contrast, have to satisfy the city council, state legislature, and federal funding sources that their computers are not being used to commit illegal acts (not that they can't be, just that they aren't). So they have to keep stricter control over the publicly-funded infrastructure to keep the various funding sources.