Back in the olden days when I pledged, we were given some VERY nice "favors". I would think the major reasons were budget (one group usually wanted to "do things better" than the other groups). Also, in a way, it was sort of a waste of money, in my opinion, why give out lots of gifts bearing your letters to people who will never be initiated into finding out what they really mean.
In some cases, it may have led to someone pretending to belong to a group but really didn't.
I guess every campus might have differences, but I would think that rules apply for formal and informal recruitment...at least "favor" wise.
My first guess in $$!!
As for sorority versus fraternity rules, that will be one thing that never will be universally agreed on! *Venus and Mars, etc.
