No it’s on the shop/seller. Been like this since 2016 or is it 2015?
Only if there is a market place it would be the market place deemed seller. It’s for VAT calculation. Now actually and company selling even 1 digital item/service into EU would be obliged to follow and register for vat but so far the EU has not many ways to go after small companies based outside EU. Same as loads of other tax legislations that copied this law.
If below 100.000euro worldwide turnover any piece of country identification is valid but you have to stick to it. Cannot use once IP and once country indicated by buyer. And as said because two need to match and only 1 piece is allowed to be users provided (like address or selected I live in country xy) you need three pieces. PayPal country is deemed user selected except for verified PayPal accounts where it would switch into being a full piece. So actually for PayPal non verified accounts if IP address doesn’t match either user selected address or PayPal country you would need to contact the buyer for clarification. E.g. a phone number verified that you can call back the buyer on is a full piece too. A phone number that is simply given but you have not verified that you can reach the buyer on is only valid like indicated address meaning user indicated piece. If all 3 don’t match have a system always the same which one you then use for vat domicile country.
Mind for US you would need the zipcode if you reach certain limits depending on the state. It’s very different based on the state and if you don’t sell much there you won’t need the zipcode either. Plus again US also right now has no way to enforce it onto foreign small companies without US presence. But yeah if IP/country determines it’s a US customer and only then I would ask for zip code.
You could still ask for full address anyhow because if you create invoices it will be better accepted by the buyer over a name only invoice without address. But it’s not a requirement in general for simplified invoices.