By my actions, I implicitly "opted in" to revealing one of my preferences to the shop owner. I did *not* "opt in" to allowing the shop owner to follow me every

By my actions, I implicitly "opted in" to revealing one of my preferences to the shop owner. I did *not* "opt in" to allowing the shop owner to follow me everywhere I go. In the online world, Google follows you almost everywhere --- without any "opt in". See the philosophical difference?