The problem, of course, is that these same thrifty people had children who grew up in the post-war era and who took prosperity for granted; since most of them only knew of the Depression from history books, it seemed as if Mommy and Daddy were being cheap just to be mean-spirited. As they matured, of course, these same children grew up to be adults who shrugged, realized that the habits of a lifetime aren't going to change just because they wanted stuff that their parents thought too damned expensive and moved on with their lives. This is why Cathy Guisewite treats her avatar's parents' habit of passing along helpful household tips on how to live on a just-treading-water budget as simply who they are; she knows that her mother and father's first and last impulse is to save money and deals with it as the fact it is because she's an adult.
Lynn Johnston, on the other hand, is not about maturity or empathy; in her mind, her mother was simply being stingy and cruel because she hated her. Since she didn't experience the Depression, it didn't happen so the habits learned during it are meaningless and evil because they got in the way of a dimwitted spoiled brat's need to get what she wanted when she wanted it. It's also why she was baffled and angered by her discovery that her mother, who still didn't spend much that she'd noticed, left quite a bit of money in the bank. I should think that Mrs Ridgway tried to impress upon Lynn the importance of doing math and being able to handle money but since Lynn didn't feel like doing something hard like that when it was easier to spend money and let someone else handle it for her, we wind up with a rich woman being paid an allowance like an infant and who cannot count past ten without removing her shoes because Mommy was an extra-bad person.