The address on the account might not be the shipping address, for example, with a gift. So until the buyer is checking out and specifies a shipping address, it would be impossible to show total price with tax. It’s an unrealistic expectation to see total price with tax on the product page when shopping at Amazon US. It’s not at all the same as VAT, which is uniform.
Of course in New Hampshire, the price on the product page
is the end price.
