It is about expectations, it is common to expected a lower price at the register or same price as on the product but not higher price. That is what drives competition among businesses that they lower prices to get more customer traffic. What would be the motivation to do opposite.
These concepts are learned at very early age when children setup Lemonade stands outside their homes or in Schools to raise money and compete with each other to see who sells more lemonade drinks and reduce price to attract more buyers, if required.
2-671 Fennell Ave. East (Door #2 with curtain on the Upper Floor)
Hamilton Ontario L8V1V3 Canada