Pretty shitty thing to say, but anyway...

Just because a few big corporations make cereal, doesn't mean you have an "illusion of choice". It's kind of how the system works. A company that makes 1 brand of cereal also makes dozens of hundreds more. They are using processes and equipment already in place to make a slight variation on existing products. It's kind of just how things work. Same with companies like Asus making dozens of hundreds of variations of monitors. I don't think that's illusion of choice. That's actual choices, with actual differences.

Anecdotally, where I live, large corporations stock the grocery shelves with all their cereals, but local companies do make it in as well. I think in my situation, I do have access to items produced locally.

If you want to make an argument that some dickhead company like Mondelez owns fucking everything, I'm right with you, but whining about cereal variety makes the argument really weak.