Re: Discount cards
"We were at our favourite BoatingFishing&Camping store and her membership had disappeared from their system, so re-enter phone number, email and details to get the 5% discount."
So, if you bought £50 worth of stuff, you gave them the great deal of £2.50 to allow them to keep tracking every purchase you make with them forever. They can also sell access to your info in their database so others can make sure the information they have on you is current.
In days gone by a loyalty card was a way to keep you shopping at the same store for a few pence in savings each time. Now they earn a few bob every month by "sharing" your information with their "partners" and you might not get those savings over what you might have paid buying the same products someplace else. I remember the days when the donut shop would hand out a coffee card and would punch it each time you purchased a coffee. After nine cups, you'd get the 10th for free. To get the same deal now, you need to get their app and fill out a questionnaire. I'll just pay full price, thanks.