> this is not true. However, the secrecy implemented around enforcement (bad publicity) causes the casual observer to think so..

That isn't the reason it isn't true. The US nominally has quite strong antitrust laws. The statutes are extremely broad in what they prohibit. But the enforcement is lacking and the courts over time have read the laws more narrowly than they were intended to be.

> the failures tend to be the ones that are amplified in media..

The failures are prolific. In a functioning regulatory environment, whether because you don't have regulations that prop up incumbents and don't create regulatory barriers to entry or because you break them up and stop them from buying each other, you wouldn't have industries where any one company has more than 15% of the market. But that is common, not rare, and that is the measure of it working.

>In a functioning regulatory environment [...] you wouldn't have industries where any one company has more than 15% of the market.

Is that realistic? Intuition is telling me that's very idealistic but I'm prepared to be surprised

> Is that realistic? Intuition is telling me that's very idealistic but I'm prepared to be surprised

There are many markets where this is the case. Which trucking company has significantly more than 15% market share? Which law firm? Which car insurance company? Which university? Which construction company?

Nearly all of the consolidated industries got there through some combination of mergers, vertical integration and regulatory barriers to entry. Even some of the "natural monopolies" like last mile telecommunications are only so because of regulatory choices -- the natural monopoly is actually the roads, which the government owns, and if they provided easy and affordable access to roadside cable trenches there would be much more competition for data service.