Markets aren't just a feature of capitalism
The Wall Street Journal put out a video about how grocery stores are an awesome example of how great capitalism is, because there is competition between food items, and abundant choices for consumers. More Perfect Union put out a video responding to WSJ, talking about how there's hardly any real competition because almost all the food in the grocery stores is owned by a small handful of companies, and most grocery stores in the U.S. belong to one of four different chains.
I didn't like the WSJ video, but the MPU video annoyed me too, because they didn't actually address the central claim of the WSJ video. There are a lot of items to choose from in the grocery store, and those items are in competition with eachother.
I believe that's true, for the most part, regardless of the ownership structure.
And I believe it's true because of markets, moreso than because of Capitalism. Capitalism is not a system of free markets, but a system of private ownership. Some capitalist activity operates in a public market - stock exchanges, amazon, grocery stores, and most other consumer-facing aspects. Other capitalist activity operates in a non-public market, through government contracts. While the Government is spending taxpayer dollars to enact it's agenda, the money is often going toward privately-owned firms, such as contractors who build schools or arms manufacturers like Lockheed. This economic activity is capitalist, regardless of the origin of the money. (people far more educated than me are probably balking at my understanding of capitalism)
The kind of response I would like to see to the WSJ video is one that addresses the central claim - that choice is available because of capitalism. Capitalism, no doubt, has played a huge role in creating an abundance of choice in our modern world. People's ability to create businesses and grow them and sell them and innovate and make new products and put them on shelves without heavy-handed government control definitely played an important role in this.
But private ownership, and especially centralized corporate ownership, is not the only way for that process to happen. Democratically owned firms can still innovate, can still produce products, and can still sell them on a market. Right now, in the U.S. there are worker-owned companies that produce products and sell them on public markets. There are also startups and small businesses that are run exclusively by the owners. Until they grow and hire employees, one could argue they are also worker-owned. Yet they exist on the market.