First world problems.
This is what happens when you have a dentist father who is making plenty of money, for a kid to think those prices are reasonable. You would think Elly is going to say, “No way,” (because that’s what you would say) but I would not be surprised to find Elly spending hundreds of dollars to buy those things for Michael and similar things for Lizzie. After all, they have a dentist father who is making plenty of money, so why not?
As for why does mom wear the same old stuff year after year? Search me. If dentist dad can afford to drop that kind of money on clothes for the kids, dentist wife can afford to buy nice clothes for herself too.