While at least 50% of the random grocery stores you would see are under one of the big 5 (or so) many of these stores are generally able to carry additional products not even necessarily approved by the top. Part of that is simply competition with local chains. And that doesn't even cover the fact that you have gobs of local and regional chains to contact and sell goods to.

But basically as a seller of lemonade you are highly likely to be able to sell your product without insane restrictions - as well have the ability to choose a chain or store that has competitive markup or a markup that you agree with.

If you sell phone applications you are dealing with exactly 2 entities that you HAVE to go through.