At a more trivial level, I an sometimes at the checkout of a store and, right before I pay, the cashier will just casually ask me for my email or phone number. My standard response is "is this information required in order for me to purchase this backpack?" or whatever it happens to be. They usually seem a bit caught off guard by this, like they're not used to having this questioned, and thus far the answer has always been no. If the answer were ever to be yes, I would not do business with them. I'm sure it's mostly just so that they can pester me with advertising, but it's the casual nature of the inappropriate request, and the seeming lack of push back from most people, that I find so repulsive.