I care if they reciprocate. I don't keep a score card per se, but I don't want anyone in my life who is only interested in feeding off of me, so to speak. Reciprocation doesn't have to be a dinner for a dinner, but there does need to be some kind of reciprocity. Otherwise I'd feel like my generosity is being exploited.
Now I know the meaning of generous is to not expect anything in return, but I save that kind of selfless altruism for volunteer work and community service.
To answer the original question, many have not and I no longer invite them over.