Are food options today not more calorie-dense than they were back in time? More easily accessible? Calories have become increasingly cheap and dense to come by. You've lots of processed food being engineered to be highly palatable and calorie dense at an industrial scale.
Plus, cars and all "comforts" eating into your physical activities?
All of those may be correlated to the rise in obesity. I see no evidence that any of them is causal. I don't even think all of them are correlated, honestly. The rise in the number of calories available certainly is, but cars and suburbs have been around longer than that. And the rise in calories may just be a response to increased demand.
Plus, cars and all "comforts" eating into your physical activities?