Georgiana was not a Lydia, rather she was a naive girl trusting an old acquaintance, actually a member of the family, and didn't consider he was a cad. I doubt Lydia took Wickham's caddishness into account at all. A momentary lapse in behavior/judgement, or in watchfulness, is not the same as habitual flouting of convention combined with parental neglect. I can't believe that the average parent of the Bennet's class in Jane Austen's day didn't have thoughts and concerns about a daughter giving away her virginity when the consequences, not just to her but to the entire family, could be catastrophic socially, economically, etc.