What I often see these days, both online and in high street shops, is that you can buy certain items at a discount with a so-called membership. There are websites (Casio Watches, for example) that won’t sell a product unless you take a membership. You see this happening in other sectors too, such as pizza chains. No membership, no deal. The fact that a shop decides whether you’re allowed to buy something is pure gaslighting, and I wonder if it’s even legal in the EU.

In Germany, grocery stores like LIDL are providing discounts if one is using their mobile applications which (if they are smart) are bound to mobile phone numbers (which, in turn, cannot be acquired without identification). Apparently, that's what one's personal privacy is worth: 11 cents off of dairy products.

Nope. (In France)

They will try to get as much info as possible out of you at the register though.

Are the prices in that particular shop very high either way? It's basically a 10 000% markup on any type of clothing anyways.

I mean, isn't this what most US based grocery chains are doing with their loyalty cards? it's not always a 100% markup, but most of the sales at Safeway/Albertsons chains or Kroger chains are effectively only good for 'members' who have provided their phone number.

I would also like to read such an article.

And what's to keep you from giving your frenemy's email address, your car dealer's phone, your college post code? I give my college zip code when pressed.

For Germany
No, at least not to the extent you describe
In Germany, there are some options involving apps and such, but they don't come close to offering the same savings

It's crazy that they do it that way in Denmark
But I can easily imagine that many others will follow suit, no matter where

Nowadays with any resemblance of regulation having fallen apart I assume they tie payment cards to tracking information anyway and the "loyalty cards" are only intended to mine customers who pay in cash.