Germany has already made statements that it will not allow other EU members to audit and collect VAT from German companies.
I'm happy that the response to this has finally changed I got downvoted to hell when commenting on the VAT changes when news just started breaking out almost 2 years ago saying that it will kill small businesses and now after the changes were implemented people actually started to see that it have.
The system completely ignores deferential VAT rates for different items in different countries, it forces businesses to register for VAT regardless if they are VAT exempt (e.g. small businesses in the UK with under 100K in yearly revenue) and it forces them to implement a "reliable system to verify the actual point of consumption of your goods and services" without actually putting in criteria on what is reliable or how you should verify the source of consumption if the first place.
"If I use a German bank card to order and item from the UK to Spain where should the VAT be collected?" To this date I haven't received an actual consistent answer or even a consistent thought process to evaluate this. And this is the most simple scenario which can be easily made more complicated like ordering an item from Germany with German payment details to be shipped to Spain from the UK, ordering an item with German payment details from the UK while you are in Spain, ordering an item from the UK with German payment details while you are in the airport in Norway, or doing the same while you are outside of the EU completely.
And these aren't complicated scenarios they things happen all the time the amount of times I had to order something I need from Amazon in the EU to myself while being in another country is ridiculous sometimes I'll order something from Amazon UK to my UK home while I'm away, sometimes I'll order from Amazon to be delivered to some country in the EU, some time if I'll need something down the line in the trip I might order it from country a to country c while being in country b.
And while Amazon could easily deal with this because they have an army of lawyers and tax advisers that will find them all the loopholes and legal justifications to continue to do what ever the frack they want, normal businesses won't be able to coupe with these types of decisions.
So far this seems to actually benefit Amazon the most because all of the people that I know that operated their own online stores for various goods and services have actually moved their store exclusively to Amazon and the likes even when they can charge a commission in the double digits just because it was the only way for them to be able to "ignore" the new tax regulations.