You may be surprised to hear that it actually is the case that retail stores are very much in the business of selling shelf space (at least in the United States - I cannot say for the EU).
It is known as a "slotting fee" and manufacturers pay it for limited shelf space in grocery stores for example. It is particularly important for the distribution of new products as stores would prefer not to take risks on an item that may or may not sell very well.
Further reading:
https://en.wikipedia.org/wiki/Slotting_fee
https://www.vox.com/2016/11/22/13707022/grocery-store-slotti...