As Omi said, all factions require a recruitment process. On top of that, with the potential for abuse on the Wild ID's "Can engage anywhere" line, it's a stricter process to accept members to ensure those accepted won't go on a shooting spree.
As far as being friendly to Nomads, while an ID may not make you green, you can RP it out that you won't be shot by Wild/K'Hara as you are a Infected. You just wouldn't be able to dock on Nom/Wild bases.