Absolutely, large swaths of the population can't do simple mental arithmetic like this at all.
The US system discriminates against those people, no denying it. That said, I'm sure our European friends are absolutely drooling at the thought of a 7% VAT...
It's just part of the price, you don't really notice.
Like I do sometimes, but then I consider VAT policy somewhat interesting, in that it specifies the "essentials" (VAT is not charged on these) of what a tax authority thinks one should have.
But most Europeans tend not to think about it on a daily basis, because it's baked into the price.
Legally VAT isn't about essentials, although luxury taxes which pre-dated VAT were often specified this way.
VAT is just a tax on Value Added like it says, and the exclusions targeting items you see as essential aren't focused on somebody's idea of what's essential but are the result of various lobbying. That is, it was not the goal of the tax system to encourage petite women to buy clothes intended for children nor to punish the largest children (or their parents) with more expensive clothes that's just the consequence of a lobbied-for exemption for kid sizes.
So "But it's an essential" is a useful emotional tactic but has no legal implications for VAT.
If you live in the San Francisco Bay area, sales taxes in SF are 8.5% Tax rates in Oakland are 9.25%. South San Francisco: 9.75% Mountain View: 9% Humboldt County: 7.75% Sonoma: 8.75%
The mental effort is not in the calculation but in figuring out what the tax rate is where you are. There really is no excuse for retailers not listing "tax-included" prices.
The US system discriminates against those people, no denying it. That said, I'm sure our European friends are absolutely drooling at the thought of a 7% VAT...