The closest analog to this in the US was a few years back, when various states were trying to collect "use taxes" from ecommerce buyers. Same concept: stateside ebay and Amazon (to cite the two biggest e-commerce sites of the time) buyers were supposed to remit sales taxes to their state of residence, but obviously nobody did. Remember when one of the biggest "unspoken advantages" of buying from Amazon and ebay was never paying sales tax?
Meanwhile states were desperate to get online sellers to collect and remit those taxes at point-of-sale. Amazon, they rightly argued, was big enough to implement this. But how in the world was joes-online-garage-sale supposed to know and keep track of the policies for 50 different states??!?!
It was a huge controversy for a long time for similar reasons (why should a 1-man business with a website do a distant state government's work? Should a buyer pay sales tax in his own state of residence, or (and?!) from the state where the seller lives? Where exactly does a large retailer "live" in relation to the brick & mortar stocking and/or shipment of goods? In which state(s) does an electronic sale take place, versus mail order? Etc...) but inevitably here we are: electronic "no sales tax" loopholes are all closed, and ecommerce sites large and small all collect tax based on your mailing address at time of sale (in the US).
So I doubt the EU and UK are going to relent on collecting taxes from resellers at time of sale: the concept has been argued, proven, and implemented in the US, it just needs to be tweaked and scaled a bit differently. It will obviously take ecommerce platforms, and Point-of-Sale/"cart api" software providers time to develop and implement. And obviously few of them want to. But again, these concepts have already been implemented into law for a huge (arguably larger and more complex) jurisdiction.
