Re: A tax on a sale...
Um, that is (similar to) VAT. Starbucks, Amazon and Google all collect VAT and do pay it to the government. Note it's a tax on the value added, not the whole of the sale, otherwise anything that is bought and resold (e.g. by a wholesaler) would get very expensive very quickly.
The argument here is about corporation tax i.e. a tax on corporate profits.