Deny you medical care payouts based on your diet. Algorithmically increase prices on you. Increase your car insurance based on where you travel.
The answer to all of these things is legislative/regulatory, not forbidding McD from collecting the most basic information about what their customers buy.
That seems fair though?
If my diet is the cause of a medical issue, then I'm the one at fault.
Car insurance should cost more if I'm more likely to claim, that's how insurance works.
This just sounds like you don't want data to force you to be honest.