FWIW, both big chain grocery stores where I live (in Canada) mark the taxes charged on each item, albeit only with a single-character code that’s explained nearer the bottom of the receipt. I’m surprised that it’s legal anywhere in our respective countries to withhold that information.

And indeed, even though you can see the nontaxable items clearly on the receipt, that’s not made clear at the shelves where the prices are posted. That’s where they really need to show the price including taxes.

Some liquor stores in Canada, for example, show both prices: before and after taxes. I’ll let you guess which price is rendered in the smaller font.