In general, I agree with you and I'm a privacy advocate. In this particular case, though, it seems like we're railing against the idea that a retailer with repeat customers keeps track of what those customers are buying most frequently and how much they spend. It would be very surprising if retailers didn't retain that info, since it's data owned by the company, generated by the core business itself, and useful for forecasting. I'm having trouble understanding the "invasive" part.

I grew up in New York state, but my dad used to shop from a company called Cable Car Clothiers, based out of San Francisco, and he'd order everything by mail or over the phone. He probably shopped there for 20 years or more before I moved to San Francisco and I literally walked by that very shop on my way to work. He knew that my new job took me by their storefront and so he asked me to go in and pick something up for him. I had a short conversation with the shop owner who had a retail system that showed every order my dad had ever placed going all the way back to the late 80s. There is a bunch of derivative data that is available when you have a log like this, like the total amount ever spent, the most frequently purchased item, date of the most recent purchase, date of the oldest purchase, etc.

Is it the scale of McDonalds that's causing concern, or is it something else?