There is probably some human who sold the ad space to somebody, and who is monitoring how many button presses there are. And they will probably put pressure on

There is probably some human who sold the ad space to somebody, and who is monitoring how many button presses there are. And they will probably put pressure on the supermarket to make sure customers are reminded that they have to push the button if they want candy. Sure, the employees are probably sick of the ad, but the people who don't have to hear the ad don't care about them :)