> This is because it is cultural.
No, it is because it is cultural you perceive the lack of the basic information about the item (the price you would pay) as a completely normal situation.
Sure, both US and Canada tax situation is a horrid mess, but at least you could know the final price if you don't have any exemptions and whatever. And if you have them you would pay less than on the full price tag. But no, both Americans and Canadians imagine some silly excuses why they can't (and hence don't want - in this order) at least to have both pre-tax and "default" tax prices on the tags.
And when I say silly - I mean it, the probably the best response I've got was "Because it would be too costly for Walmart to do so, they have too many shops - they would need too many new tags to replace". Literally. On my question how do they manage to replace their tags now (especially when there is special offers, seasonal offers, holiday offers or just a plain price changes) and how this would be a problem for a company with US$13.67 *billions of NET income* I've got just downvotes and silence.
And the most astonishing thing is what many seriously think there is no way to compute the tax beforehand to print it on the tag. On the reasonable question why then it could be computed at the till and how many times a day the tax policy change ("But they would need to change the tags so often!" - same people) I again receive the silence at best or "It is how we do things."
> amazon in the UK, to ship to me in Canada, I get told the wrong price, because silly VAT is built in.
Well yes, Amazon.co.uk is mainly for people in UK so of course they would prefer to see how much THEY would pay, not £249.00 on the tag and suddenly £281.3240 at the checkout.
I didn't buy from UK for a decade, but last time I checked you would see the VAT cost at the total, eg at apple.com/uk/shop just now: £949.00 Total Payments for your device include VAT of approx. £159.00.*
Some world-wide oriented sites just show both VAT and VAT excluded prices.