Anti-trust is very hard, and extremely hard post-Bork. You have to prove that the consumer is being harmed, and ultimately once you do prove that, you have to seize entire companies to break them up. That requires an extreme exercise of government power. Meanwhile, governments have always had the ability to tax, it's not new. Progressive taxation is what's supposed to stop wealth accumulation, and therefore the accumulation of political power, but what's actually happened is that we've reverted to a regressive taxation scheme, where the professional class/upper-middle class and mid-size companies pay the bulk of the taxes, while ultra rich individuals and rich corporations pay effectively nothing in taxes.
The less taxes the ultra rich pay, the more YOU have to pay to make up the difference. Why anyone in the 125k-300k income range would be against taxing the uber rich is beyond me.
Elected politicians in both parties align themselves with corporations for political purposes (and the few that don't are labeled socialists, go figure.) It's the same reason Mitch McConnell said "corporations should stay out of politics, but keep donating money to politicians."
Ultimately, it's not about the elected officials, they are all effectively whores for as long as they have to continue collecting money to get re-elected. It's about the courts. Republican-appointed judges are more likely to decide in favor of more corporate power, while Democratic-appointed judgements are more likely to decide in favor of workers or consumers. That's what this is about. The reason our anti-trust enforcement has been lax for 40 years is all because of Robert Bork, a Republican judge who Ronald Reagan tried to put on the supreme court.
en.wikipedia.org
Further, Republican-appointed judges are more likely to rule in favor of unlimited corporate political spending, while Democratic-appointed judges are more likely to rule to limit corporate political donations.
So yeah, both parties are taking us on the road to corporate feudalism, but one of them is at least hitting the brakes occasionally while the other is stepping on the gas the whole time.