Why can't you control companies like that? Why do they have to be privately owned by a small group of ultra-rich? Why should they get to make decisions that affect people's lives without any input from those people?
I guess its where the term capitalism came from. Why do they have to be privately owned by a small group of ultra-rich? Because it needs capital to start it. This is where banks come in or these days venture capitalists. In some ways it is now possible to create a product or service and have it marketed and viable as a revenue generator due to the modern internet communication revolution. In the past historically the rich as land owners or via heredity or the merchant class had a means (capital) to generate money. Hence the rich got richer. Of course if you understand things like the power of gearing your returns can be great. Ideas too and in course in particular in modern times can be the source of value. The pen is indeed mightier than the sword. Unless you balance things out across the many (you can argue this is where socialism came from) there is not the critical mass and importantly decision making (= power) that creates value.
Or put another way name me one significant business or organisation today that has such an influence from having started from the many. Very few right? It cuts across all forms of modern life and where wealth is created and is generated and perpetuated. Sport (rich players - the few and not the many. Film Stars. Pop stars. I could go on but you get the idea.
Politics of course should be where it can be addressed and yes the many, with little individual power, can be enfranchised but its sad to say political history (as far as I am aware) in any country has never really succeeded in a genuine wealth distribution from rich to poor. Taxes may work but it is the rich that are best placed to reduce (though fair means or foul).
There are companies (co-operatives) that do in general achieve the aim - the benefits shared amongst the many members. But in business terms those types of businesses are well over shadowed by the larger organisations where ownership is shared by the few (even in large PLC's where in reality it is hedge funds and the like that can hold a good percentage of the capital and smaller or private companies are held by a much smaller group.
I am probably oversimplifying but even as far back as Plato in his Republic argued that everyone has a natural role and society is best served if they were to do that. In principal yes (maybe) but I don't think politics (or in reality Politicians) bar maybe a few have ever tried to ever imagine that utopia is even remotely possible.
Again a much better historian could probably argue otherwise but I can't think of any modern day examples where this can be argued as true.