Since you want to get to the root cause and we're talking about USA, I believe that would be the American people.
Also - corporations are full of people. And those are all Americans. Even lobbyists are Americans.
But we should do something useful, and we're looking for easier targets to focus our rage and aggression on. I recommend those being the people that explicitly have been given power. Based on what I know about the American constitution, I believe that would be the government.
> Government has legislature and litigation focused on big tech right now on multiple fronts.
If corporation gets a fine that's lower than their profits from breaking the law, then it's not a punishment but government getting its cut. Prosecuting few low hanging fruits doesn't make this administration any less neoliberal than previous ones, also remember that they will get prosecuted mostly for stealing from richer.
Also - corporations are full of people. And those are all Americans. Even lobbyists are Americans.
But we should do something useful, and we're looking for easier targets to focus our rage and aggression on. I recommend those being the people that explicitly have been given power. Based on what I know about the American constitution, I believe that would be the government.