Sorry for the late reply.
Slovene "Media law" (http://www.pisrs.si/Pis.web/pregledPredpisa?id=ZAKO1608) effectively states that any registered media and it's editor-in-charge are responsible for all content published in/on their media assets, regardless if it comes from the newsroom or is UGC.
That includes making sure that authorship of the published piece is confirmed - the editorial board may decide to keep the author anonymous in the publication, but has to state that it is having his/her confirmed name on the record. It has for decades been a standard practice in printed UGC, like readers' letters section, as the very limited number of submits were easy to handle.
Real name and address validation can be checked against public records, while the ID of the UGC author is actually confirmed via a call back to the person submitting. Valid contact information is vital for UGC to go through. The UGC author is then signed under the post with name, surname and place of living. At least that's the theory and hopefully most media outlets do do it in full.
Here's the thing: due to outdated and/or vague definitions in the law, on top of an avalanche of UGC on the web, media outlets (and regulators for that matter) forgo this same rigour on the web, posting the comments without proactive moderation, only moderating post-festum, if at all.
The latest version and interpretation of the law is however stricter in holding the media and it's editor-in-charge accountable and that has prompted the outlets to rethink their online commenting sections.
The solution at Dnevnik essentially transplanted the UGC logic and processes of the print publication into the online submission form, requiring personal detail & contacts as per law, explaining the requirements aside of individual input field. Wish we could provide better UX, but as said before, our resources we're limited.