The state and large corporate interests in the USA are very tightly integrated and have been for at least an entire generation.
The American government does serve the interests of the American people: the American people who own the bulk of the land and the largest companies.
George Washington was the largest landowner in the colonies when the revolution started.
The idea that the US was originally founded "by the people, for the people" is not at all what happened. I guess we could say that the government they created was progressive for its time, at least.
Slaves would not have been a large proportion of the country as a whole--about 20% at their height. While the early US did require landownership for adult free males to vote, the US also had unusually high landownership rates. It's estimated that ~60% of free adult males had the right to vote (contemporary Britain had about 15-20% of free adult males having that same rate). So ultimately you end up with about 25% of the current franchise rate, or somewhere in the mid-high teens after taking into account the existence of children who still cannot vote.
The law doesn't require this of course, but basically all money managers get their insider trading compliance program from the same 3 outside law firms.