Tesco are a disgrace! Charging higher prices (sometimes stupidly higher prices,) for something, if you don't have their clubcard.
Morrisons do it too, but their prices without a storecard aren't quite as bad - it's still about 15-20% higher without one though. I do actually do some shopping at Morrisons, but hell will freeze over before I get a Morrisons 'More Card.' Not only do I not want my data harvested, but also, I don't appreciated being coerced and bullied into getting their storecard.
Tesco are far worse. Charging a little more if you don't have a storecard is fine (like 5%) but some things in TESCO, are 50% - 60% more, and some have an even higher % than that added on. A few things are double - or more than double, without a storecard. Nasty.
And for this reason, I rarely go in there. I spend about £70 a year in Tesco.
As a few posters have said, you don't pay LESS if you have a storecard, you pay much more if you don't have one. At one time, supermarkets would let you collect points for every purchase, and then when you'd got so many, you got vouchers for money off.
Now, they are practicing underhand tactics, and making you pay more - a LOT more - if you don't have a clubcard.
Why are they all so desperate for people to have one?
Stores trying to force you into clubcards is one of the reasons I do 75%-80% of my shopping at Aldi and Lidl.
Someone put on Twitter the other day that Tesco are basically bullying people into having their clubcard at this point, and they're right.