That you couldn’t give a hoot etc. shows that you don’t really understand what is happening or are very naive. Nothing wrong with that, it’s normal, but it is worth looking into a little deeper, especially stores like Tesco. When prices are already artificially higher than they should be, and they are trebling the price of some items to get people to get their cards, you should be wondering why. They are not only making money from selling the items, but from selling your data. They also use the data in many ways, probably many unethical. With that much power and money and what is going on around the world currently with lobbying etc. it is definitely something that should be looked at. You should look up personalised pricing as well as here and you might start to notice that you have paid for those trips to Alton Towers and Blackpool (probably twice over). With a few companies trialing software as we speak. New York introduced a law too.

As for the imaginary markup

Tesco

LIDL

ALDI (No discount card)

SuperValu ‘sale’ price but applicable to everyone not cardholders.

Dunnes Stores Same as above

Centra €0.59 same as above and Centra are known for being more expensive

They are also €0.49 in Londis, Gala, Daybreak and Costcutter (no online listings) and €0.59 in Mace and EuroSpar (also known for being expensive)

The list of products that it happens with is huge, you could check the same wherever you are.