@kmic

So for example in Poland for years you needed a stamp on a VAT invoice, and then the invoice had to be signed.

And not only contain a signature but actually signed in a way that proved it was signed by a person, rather than printed with a copy-paste signature, so effectively you had to use a blue pen for signature.

In case of electronic invoices it was so extremely stupid and unusable that nobody actually used them because it was just risky.