Why shouldn't digital goods be subject to the same taxation? If you bring blurays across borders why does that incur a tarif when a download doesn't.
Where do you apply the tariffs?
Does every nation in the IP chain get a cut, you did use their infrastructure after all, or do you only pay at the point of consumption? What happens when it's a multi-port stream being sent in pieces from mirrors across the globe, are there different tariff rates based on the source of each specific portion of the stream or does it only count from the nation which runs the service and where you're buying from?
What happens when you're redownloading a file you already "own", do you need to pay tariffs again or will the stream be flagged as already bought? If an "already bought" flag exists, how do you prevent someone from spoofing it to avoid paying the tariff?
To prevent that kind of fraud at the national taxation level wouldn't they require regulatory bodies in each nation to have a repository, tied to your legal name, containing a list of all the digital goods you "own", so you're not charged a second time? Wouldn't every single potential nation worldwide need to have this list in case your file request is somehow routed through one of their country's servers, stopping them from charging their portion of the tariff? What if some of those less reputable nations magically "loses" your purchase history and charges you the tariff anyway, who do you go to to get that recovered? Or will the amount be so small no one bothers, thus leading to rampant fraud by the third party corporations paid to administer the program who'll just add those "illegal" overcharges to their bottom line?
How would something like this align with global privacy and the protection of human rights? Some might not care if the feds know they bought "Paw Patrol" for their kids, but what about authoritarian regimes - would you want some dictatorial nation state's loyalty office targeting your family who might still live in their police state hellhole because you'd dared read Orwell's 1984, Bradbury's Fahrenheit 451, or Attwood's Handmaid's Tale in a nation which has a stable democracy and might talk about it with your oppressed family?