This belief is held by many older folks due to propoganda, and it is passed down to their children when their parents teach them about taxes. Since almost all younger folks use automated tax services, if they aren’t doing the math themselves, the fact that this isn’t true isn’t going to be discovered. I was taught the incorrect way when I was a kid, but noticed that it was wrong the first time I had to do my own taxes. But when I told my parents the way it actually worked, they didn’t believe me until I showed them the .gov site that breaks it down. I grew up in a small, blue collar town, and every single person I talked to about taxes parroted the same incorrect system.