>> Even taxes should be included in prices.

Many people are dumb as bricks and hold insanely weird beliefs such as "if the displayed prices include tax, you will become desensitized and won't notice it if the government increases the tax rate!" or "I want to know exactly how much is going to the business and how much is going to the government!" Some US states have even codified this and explicitly ban tax-included pricing.

This is also why people will fight tooth-and-nail against very obvious methods to drastically simplify things, such as by having the IRS handle your taxes for you and simply send you an "is this correct or do you need to make changes?" form every year.