Who are the "current powers?" The current view of antitrust law has been operative since the 1980s, and has encompassed administrations on both sides of the fence. It's rooted in a large body of academic scholarship that has withstood the test of time.

Your comparison to health care is telling. You make it seem like it's "rich" "party donors" who are opposed to single-payer healthcare. In reality, just 21% of the public supports abolishing private insurance (which single-payer healthcare necessarily would require): https://www.mrctv.org/blog/cnn-poll-only-21-favor-getting-ri....

There is a rhetorical tendency to blame American public policy on conspiracies rather than honestly attempting to figure out why people vote the way they do. In the context of healthcare, for example, isn't it possible that people (1) reasonably believe that single payer won't be a magic bullet that lowers our healthcare costs to European levels; and (2) don't want to pay the additional taxes required to pay for universal coverage, when most people who aren't on Medicare receive healthcare from their employers?

There is, in fact, good evidence that those factors, rather than "rich people" and "party donors" are responsible. You'll notice that no Democrat that supports Medicare for All has offered a serious health care proposal, i.e. one that raises taxes sufficiently to pay for it. That gives you a remarkable insight into voter dynamics! Even Sanders is afraid to propose the $30 trillion in new taxes that will be required to pay for Medicare for All. (His menu would raise just $10-12 trillion, even if all options were adopted.) And while he is quite happy to propose tax rates on the wealthy *higher than those in France—51% versus 45%—he is unwilling to propose raising taxes even on people making up to $250,000 to anywhere near French levels. What does that tell you about what people want? Who is he afraid of? The rich? Or the suburban married couple making $125,000?

Maybe Americans aren't irrational. Maybe they like having 50% higher disposable income compared to Germany or France. Maybe they don't want to pay a 20% VAT, the OECD average. Maybe they don't want their FICA contributions to double or triple, bringing those in line with social insurance taxes in Germany or France. Maybe they don't want 40%+ tax brackets to kick in well under $100,000, like in Germany, France, Sweden, etc. With respect to antitrust, maybe they like the rock-bottom prices enabled by the scale of companies like Wal-Mart and Amazon. Maybe they don't support carbon taxes because they like $3 gas, road trips, and SUVs? Maybe they are voting for the "powers" that give them what they want?

It’s interesting to note that at the time the Microsoft antitrust decision came down, polls showed that people were opposed to breaking up Microsoft 54-35. That was the case even though a majority of people thought it was a monopoly! I don’t think people usually can articulate a specific opinion on antitrust issues, save for high profile cases like that, but people don’t vote for specific policies, they vote for an ideology. And for decades, they’ve been voting for a deregulatory ideology that features less government intervention in the economy.