you cannot compare eroski (for example) with Corte ingles
the first is a supermarket while the second is a department store.
I like to shop in el corte ingles as it does offer a wide selection of products, etc… But if you are looking at budgeting on groceries and such, eroski follows a far more ‘tesco’ orientated approach. With own products being substantially cheaper due to simpler packaging, etc…
And the fact that it might be the most famous and successful worker’s cooperative in the world is quite interesting (in my opinion anyway).