Your statements about Germany are not correct: Factur-X is not common in Germany at all, the German version of this standard (albeit very closely related to Factur-X) is called Zugferd and it is by no means mandatory in Germany.

Actually, most governmental agencies (which have required e-invoices for many years), only accept the pure XML files. Zugferd is a bit of an interim solution until everybody is familiar with an e-invoice visualizer. There are already many free (as in beer and source) solutions available for that. Zugferd (X-Factur) is a problematic standard, because there can be discrepancies between the PDF and the embedded file and its unclear, which is authorative. Concerning the platforms: I don't know about France, but in Germany, sending e-invoices by e-mail is explicitly permitted by the government.