Yeah, I understand. It's definitely not ideal and I don't want to sound like I'm condoning it because it really should be improved. I'm just not sure there's an obvious solution given the US/Canadian regional/local autonomy over sales taxes, but I'm glad to hear ideas. Most towns in California, for instance, have their own sales tax rates and while this could obviously be accommodated in retail spaces (at the cost of confusing national advertising?) it makes displaying prices rather complicated on online marketplaces which currently add taxes once a shipping address is entered during the checkout process. In contrast, despite the reasonable regional autonomy in Switzerland (not too dissimilar from states in the US) a national VAT rate avoids this issue.
The obvious exception is for marketplaces that sell to other markets. For instance, the prices on Amazon.de (Germany) change if a Swiss shipping address is entered due to the different VAT rate.