Yes, but the US consumers are conditioned to see one price and pay a higher price. You and I might see +40% and think "that's too high a percentage". Others see +something and think "just like every other time". If they even look - I'm sure these items are often in a cart with many other items.

The stores get away with it because even when ignoring the fact that tax is added after, few of the shoppers in these stores will remember the shelf price for a basket of 20+ items from the store. They might remember one or two, but they won't remember (and therefore will not notice) enough of the shelf prices to notice the systematic overcharge at the register. In reality, a good number of the shoppers likely don't remember any of the prices from the shelf tags, and will not be mentally summing up what the final price should be, so those shoppers won't notice the discrepancy at all.

I'm pretty sure the problem is "companies try to screw over poor people", and not "the sticker price doesn't include the tax".