On Aniro the assemblies were not all the same. Depending on countries the protocol was different, sometimes heavy, maybe impractical, but this give spicy, and fits to the Lore. For example it was common to mock the impossibility to attend to a chamber of Nobles without invitation if you were not a subject, even for a ambassador.
(ooc) On Leanon, none was allowed at the Chamber of Nobles but the Nobles and the Ambassadors (on whose the Chamber had to agree). There were - very, very rarely - public assemblies. (ooc)