sole proprietor
partnership
llc
corporation
ect...
all they are are ways of structuring ones business. In many cases for the sole reason of limiting liability.
I see no compelling reason that someone who owns a widget factory who incorporates it has any fewer rights than he would if he ran it has a sole proprietorship.
A sole proprietorship is a form of informal incorporation. So is a partnership and LLC. Each of those terms is described in detail in the tax code, and have specific individual corporate identities and requirements - and tax rates.
But just human beings making and selling products? You will not find that phrase in the tax code.
These terms are the basis of administrative law. Whether you “drive” or “travel” is two different things. Yes, it’s bullsh!t - but it’s how it works. It’s a word game, and a presumption game, and it’s played deadly serious by the government. It’s why cops and lawyers and judges and bureaucrats talk the way they do - so stilted and weird. Notice in the article - the writer says “business.” But what does the Justice ask about in his question? Corporations. Not businesses - corporations.