Because there's a large number of us who want to pay with that data and don't think it's as damaging as cutting off our arms. It is true that there are things we are not allowed to freely exchange: kidneys, livers, most parts of our body. It is true that there are things we are allowed to relatively freely exchange: money, possessions, plasma, blood, and currently data.
Lots of us feel that the data thing should be allowed. That's all.
Lots of us feel that the data thing should be allowed. That's all.