This wouldn't be that difficult, except for the fact that do you realize how many times these groups forget to even ask for their allowed discounts? I know the question is rhetorical because I know you know this.
There is no way Disney will ever implement a system that effectively works against them. The converse argument being that if they did, imagine the great PR They'd get and the potential gain they get in spending that might otherwise not happen (Trying to be creative here to justify. LOL).
Prepared to eat crow and hoping I have to. I don't feel very hungry though, unfortunately.