That would be nice, but there is a LOT of background work before that is feasible (in the US). As it currently stands, for many products a vendor would need to know who you are and where you live before they could quote you a total price. That's unacceptable.
but you did say that figuring out the final price is "unacceptable"? why is it unacceptable? my point is that other countries have figured out a way to display the final prices, but USA still hasn't figured out how to do it or they don't have any plans to do it.
Actually there's a purpose to keeping taxes separate. Policymakers want the tax burden to be visible, it is not part of price transparency because the vendor has nothing to do with the tax rate.
