If you eat 2 happy meals, you pay for 2 happy meals....

I think if your fat @$$ uses two seats the same should apply. As for the idea of making different sized seats (small, medium, and large) most of america has gotten too cheap and will chose what is the cheapest, reguardless of comfort. Ever seen the person trying to get on with thier <2 year old "lap child" who is going off to kindergarten tomorrow?