There is far less competition than it appears, which is why brands are so important for maintaining the fictional appearance of it. This is why some of the left say "there is no ethical consumption under capitalism" = while it's a crappy slogan, the reality is that many well-meaning consumers who try to vote with their wallets are just picking 'nicer' brands but still giving their money to the same places, and their buying decisions have far more influence on the way goods and services are marketed than the way they are produced.

Now, in some places you can absolutely vote with your dollars, buying locally produced food and keeping the money circulating within your community and so forth. But that's also a bit of a luxury choice - you're willing to pay a bit more, and have the know-how to figure out the difference between a genuine small business that's doing right by its employees/the environment/whatever you care about, and a hip brand that is associated with those values but actually yet another front for a large corporate concern. Many people don't have those choices available (their only buying options maybe through superstores like Walmart or Dollar Tree), or lack the insight to see through the multiple layers of marketing and the economic pros and cons of our complex business infrastructure.

Unilever and other big conglomerates do actually put their logo on the products so if you pay careful attention you can see that information just by inspecting the packaging at the supermarket, but to most people that's just another certification stamp.