UK supermarkets (and I assume many more around the world) have done this "discount" for PI trick for decades.
It used to be that you'd get a 1% cashback (in vouchers), but they realised people weren't bothering when just spending a few quid, so they hiked the prices from £3 to £4.50 then offered a 50p discount for your PI.
It used to be that you'd get a 1% cashback (in vouchers), but they realised people weren't bothering when just spending a few quid, so they hiked the prices from £3 to £4.50 then offered a 50p discount for your PI.