Bread was just an example. Just try to open a small corner shop and see how easy it is. Almost any small business has legal obstacles and a barrier as a high to entry as a large corporation. While the corporation can pass that barrier, little guys can't.
> Want to make screwdrivers and sell them to the local hardware store? Go ahead.
I doubt you can do it without having to pay attention to thousand of different regulations.
It's only when you start making all sorts of things for yourself that you really start to see how completely irrational the markup on many things is, which then begs the question - why isn't anybody simply dropping the prices by 50% and making a killing? And the only answer I can really see is because it's become really quite painful to be able to sell things in America, unless you want to go all-in on it.
I'd also add that in terms of food safety, the big concern is not small business, but big business. Buy food from an individual or a family and you're eating what they're also eating for dinner, and probably have been for decades. By contrast at e.g. McDonalds, those executives probably aren't touching their "product" except for photo ops. Their only motivation is to maximize profit, which often comes in the form of sacrifices in quality or even safety of what's sold. [1] And this has always been true. "The Jungle" wasn't about Joe Bob's streetside shop.
[1] - https://www.meatpoultry.com/articles/20650-lftb-to-be-classi...
Sure if you bake a few loaves of bread at home then that probably seems cheap in terms of ingredients. Now add in your labor, allocate costs for utilities and kitchen appliances, and figure out what it would cost to drive around all day delivering that bread to retailers. Suddenly it's not so cheap.
Some states such as California do have special exemptions for "cottage" production of low risk foods such as bread.
https://www.cdph.ca.gov/Programs/CEH/DFDCS/Pages/FDBPrograms...
In other industries it's much easier to legally start selling things. Want to make screwdrivers and sell them to the local hardware store? Go ahead.