A store wants profit making products at the eye level of the targeted consumer, lower for the child oriented products and higher for the adult oriented ones. Smaller vendors have to pay, in some way, for the "premier" space and facing width. So, certain items obviously get more "facings" and the "prime" space. It's only logical.
Now, if a producer comes in offering a new product, to be accompanied by a promotion campaign, heavily discounted to the store, good space will be found (up front, near the registers, perhaps a temporary, introductory "island" display. etc) just to see how the product performs. Manufacturers/wholesalers make their product profitable for the store or, the product doesn't get a "showcase" area.
An Albertsons owned chain has steadily built up a great reputation for "house" branded products over the years, this is why such product gets premier display space to the dismay of Campbells, Eggos, Kraft, etc.
And yes, there is a fine line when it comes to legal/illegal discrimination against smaller vendors. One needs to remember the "golden Rule", "He who has the gold makes the rules."