Because big corporations tell us what we like and don’t like. People who can toss 90% of their income into stocks/investments etc… that can be used to make more money, would rather have as much as possible. Hence they preffer the costs to go onto when you are purchasing things. While poorer people obviously are spending most of their money on things.

In short it’s a way to keep taxes lower for people making a good amount of money, Especially makes things better for those who can invest and multiply their money.