The entire point is that having mega-corporations like Amazon or Walmart is not the goal, their very existence should be prevented.
The entire point is that profit at all costs, the very system you defend when you describe it like a natural law, is a pure dystopia, and shouldn't exist.
Having many small, independent stores is desirable not even just because of competition, but also to provide an environment that allows a certain kind of society to exist in the first place.
A society where american mega-corporations are dominating while avoiding taxes kills competition because smaller competitors don't have the same advantages. You end up with huge stores at the edge of town, as walmart often does in the US, and as result destroy walkability and accessibility of the entire urban environment.
I live in a city in Germany where exactly that is happening. I'm now 22, in my childhood we had dozens of stores nearby. Two small supermarkets, a drug store, two pharmacies, three bakeries, a post office.
Nowadays out of all these, one pharmacy and one bakery are left.
The next supermarket is 2km away, and everyone drives there.
Instead of parents sending children to go by foot and buy that loter of milk they forgot, they drive every time.
As result, roads got more congested and had to be widened. Sidewalks were the first to be removed or made smaller to give way for more lanes. Also, walking to the stores you'd always meet other people, and walk together and talk.
In 18 years, this district went from being a walkable place with a healthy social environment to a suburban hellhole, just because larger chains built ever larger supermarkets and killed the small competition.
I'm moving to a different city in a few months, one where this hasn't happened yet, where everyone, child or adult, can still reach everything by foot, and where the streets are still calm enough that children can walk on the wide sidewalks without much risk. A place where there are still many smaller stores, each selling different stuff, giving together much more choice than the big retailers do.