It's very sad we have to legislate common sense. But you know what "they" say about common sense. It isn't very common at all.
I can agree with this. I think we all know some things are NOT good for society as a whole: obesity, smoking, alcoholism, driving without a seat-belt or whilst on the phone. It benefits us all to reward good behaviour and discourage bad behaviour. The cost of obesity on the public health system is immense and rising yearly - maybe I'm not keen on MY taxes paying for other people's shitty personal "freedom" choices.
The Aussie Govt. is currently spending Aussie tax payers money on education programs in schools, advertising campaigns, money into the medical system to educated people in our society about obesity, healthier eating choices and the importance of exercising every day (ads on the radio and TV are currently running). It's a more subtle way than banning soft drinks and fast foods, there has also been discussion about higher taxes on fast foods here too.
So your taxes are already paying for other people's personal "freedom" choices....