I stood in a store where one such principle is to offer a collectible toy if you spend over a certain amount. I saw children pressuring their mom to spend more to get a toy. this happens at the till point where there is sweets in abundance. So to keep the toddler from having a meltdown there and then the mother grabs something just to get things done.
https://moneyworm.home.blog/2019/06/05/supermarket-tactics/
https://moneyworm.home.blog/2019/06/05/supermarket-tactics/