Himaginn said:
Because that is the mechanism used. If you know of a better one I'm sure they'll be pleased to hear from you.
What's wrong with permitting free trade of goods with each country deciding on the tax for itself?
Are you aware of how sales tax works over here, in broad terms? There is no national system, each state operates its own entirely distinct system, and while the rules within each state are consistent for what's taxable, what isn't and so on, the actual rate applied can vary even within a state.
Here in California, for example, the basic rate is 7.5%, the bulk going to state funds and a little to the county where the sale takes place. Some counties and cities apply their own small additional tax, e.g. where I'm located in Shasta County the sales tax is just the basic 7.5% across the whole county, except in the City of Anderson a few miles from here where it's 8%. Down in southern California there are places where the rate goes up to 9 or 10%. And in this state, goods are taxable but services are not (there are exemptions for some goods as well, notably food).
Go to other states and you'll find compltely different state and local rates and completely different rules about what's taxable and what isn't. Drive about 120 miles from where I am across into Oregon and there is no sales tax at all.
This is all within the "common market" of a single country, and it works just fine.
Yet the EU seems to think that the exact same rules - and, eventually, the exact same rates - should apply not just across a single nation but across an entire group of nations.
BTW, It does ensure freedom for consumers to choose which products they prefer, rather than then ones proscribed by individual governments or dumped on us.
People are still free to choose. It's just a matter of weighing up the costs, as they already do when selecting between two different items from two different manufacturers, exclusive of any tax issues.