I wish they would treat sales tax as a hidden fee. Just show the actual damn price up front plzkthx.
If we had a standard sales tax, sure. But when sales taxes vary by city and county, like they do in California, it's very painful to do that -- and that's only 1 of the 50 states!
Sure it's hard. Do I care? Not in even the slightest. I have not one picogram of care.
The calculation is made at the point of sale. They can list a final price and work backwards. Does that make it harder for a business to set the price? Yeah maybe. I still don't care.
It's a clearly solvable problem. It'd provide a superior consumer experience. It'd be slightly inconvenient for businesses. SHIP IT.