How do you claim bounties? How do you take out an unlawful donning a FL IFF? A hostile combatant on a neutral IFF and so on and so forth?
Swell idea in theory, in practice it cannot work.
You have to accept that for rules and gameplay purposes, ID's ARE AN IN-RP ITEM.
Besides, that way you make sure to avoid another point of contention that will surely lead to many an argument about what players know and don't know both in-game and out of game.
P.S. Yes, personally I do think IND is a redundant faction, everything could be done on an IC ID, as an IC subfaction. If anything, I'd like to see fewer ID's overall. To say that you can't roleplay a specific role without a certain ID is like saying you can't roleplay a particular character without using certain naughty words. Be creative!