I agree than tracking detailed purchase data can lead to serious discrimination and inequity especially in a dictatorship. The use case in your example, however, seems fair:
* The person has a choice whether to consume fast food regularly. It’s their freedom, yes, but they should also accept the costs that come with their lifestyle choices. Similarly, if someone chooses to regularly drive at a daredevil speed, they should pay a higher premium.
* This is different than discrimination based on involuntary characteristics. If someone is born with genetic predisposition to get cancer, or happens to grow up in a city with high carcinogen level, it’s arguably a lot less fair to charge them extras.
* The person has a choice whether to consume fast food regularly. It’s their freedom, yes, but they should also accept the costs that come with their lifestyle choices. Similarly, if someone chooses to regularly drive at a daredevil speed, they should pay a higher premium.
* This is different than discrimination based on involuntary characteristics. If someone is born with genetic predisposition to get cancer, or happens to grow up in a city with high carcinogen level, it’s arguably a lot less fair to charge them extras.