Dora's immaturity is probably a combination of natural tendencies, gender norms, and her wealthy upbringing: her remark that she would tell a servant to make dinner would be perfectly acceptable if she were marrying an upper-class man, but she hasn't learned the skills to run a more modest household. In any case, even David's attempts to dress up practical skills like account-keeping in more ornamental terms (for instance, by giving Dora a "pretty" box for her pencils) go nowhere. Tellingly, she puts all these practical household objects to purely frivolous use by teaching Jip to do pointless tricks with them.