Given that they have no house elfs, she had to leave Malfoy Manor with a scandal and learn how to do things by the book. Like, muggles have books on how to be a muggle. So, she learned that you have to do things a certain way.
Meanwhile Harry never had nice things worth caring about, and he was raised in a household with modern, low temperature laundry detergent. So he is used to throw everything together, because at 40Cº color bleed is negligent for modern clothing that you don't particularly care about.
But now blacks include wizard's clothes that bleed a lot of colour due to inferior technology, and his habit now causes a lot of problems.
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u/Miku_Miku_Mayhem 3h ago
Malfoid is a pureblood, i doubt she even knows how to operate a washing machine.