Is she really better with money than he is, or did she grow up rich?

There is a big difference between the financial security of someone who grew up with rich parents and someone who didn’t. Two people could be earning the same relatively low salary and be in completely different financial places. Someone with rich parents probably didn’t have to take out student loans to go to college, so they enter the working world without debt. Their parents might not pay their bills, but they might give them cash to save for retirement, unlike someone whose parents are struggling financially themselves. If your parents can’t pay their bills, you might feel obliged to send money back home to support them. If you’re only making $45K, you can barely afford to support yourself, let alone your aging parents! 

The couple in this story are in very different places financially. They have the same salary, but their parents’ financial situations inform theirs.