They use a home-grown solution called FatturaPA. It was originally meant to be used for sending e-invoices to government agencies and public administrations, but it was then expanded to all businesses and made mandatory in 2019.

In their denfese, they came up with the system before 2013. But I think it should be time for the EU to step in and force a unified system across the Union (e.g. UBL / CII).