The problem is, most of corporations are rich enough to be completely able to possess their own security - even in real world you don't see police or military covering mere supermarkets or production facilities (however powerplants or dams are exceptions here, as they are vital military objects). Also, don't forget those aren't just one company, but entire corporation, so they own many subdivisions, firms and businesses or even brands - like Detroit Munitions being company belonging to mother-company, Ageira.
For more ooRP reasons: we have too small playerbase to do that, so it won't work. We aren't EVE. If it wasn't the case, we would still see Mercenary and Trader ID, which were fused with Freelancer ID.
