Re: TL; DR
> just as how no Brexiter can explain one single measurable thing that will improve post-Brexit.
The new Digital Services Tax was delayed while we waited for the EU to introduce its own version, but in the end we went ahead anyway.
We're not alone: France, Spain and Italy have all decided to press ahead with their own equivalents without (or despite) waiting for the EU.
Disclaimer: the OP asked for one thing. I am in no way suggesting that this one thing on its own justifies leaving or remaining.
Biting the hand that feeds IT
