to give an answer to a rhetorical question: because firing people based on weight is a can of worms being opened. while it's still technically not illegal to fire someone because their weight makes them "unfit," the ada can be invoked if said obesity is caused by a disorder (e.g., type 1 diabetes). this ignores the fact that it's hard to prove that someone would be unfit just for their weight; it just opens up employers to lawsuits.
a simpler way to think about it would be to ask yourself if the guy handing out speeding tickets is "unfit for duty" solely because he's obese.
to give an answer to a rhetorical question: because firing people based on weight is a can of worms being opened. while it's still technically not illegal to fire someone because their weight makes them "unfit," the ada can be invoked if said obesity is caused by a disorder (e.g., type 1 diabetes). this ignores the fact that it's hard to prove that someone would be unfit just for their weight; it just opens up employers to lawsuits. a simpler way to think about it would be to ask yourself if the guy handing out speeding tickets is "unfit for duty" solely because he's obese.