The monopoly provisions of the Sherman Act, as I understand them, only go into effect only for one company, not an oligopoly like we have in cell phone services and media. So in order to get a judgment against oligopolies, we must rely on collusion, which is notoriously hard to prove. Collusion is an intentional act, like a discussion to agree not to compete on prices. If you just happen to have the same prices, the theory goes, that's just the market doing its work and thus it's the "right" price.
The problem with current antitrust laws, though is that they were written ages and ages ago. The Sherman Act was passed in 1890. You know what didn't exist in 1890? The internet. We have basically perfect information these days. In 1890, we could trust competitors to engage in price wars, partially because they don't know what the other one is likely to do, and thus they will go as low as possible to try and outdo whatever their competitor is capable of. Therefore, the only likely way to end up in an actual equilibrium would be either collusion or the market actually driving the price down to near cost.
Today it's different. It's unbelievably easy for an employee of AT&T to look up T-Mobile's prices on their website, or to have a script look up all their competitors prices. This means that a company can react nearly instantly to another company lowering its prices before anyone even notices the difference. Well, if a company can react nearly instantly, what incentive is there to proactively compete on prices? I can't see any. Say there are only four companies in a market, and they all charge the same minimum rate for a service - say, purely hypothetically, $40/mo for minutes many people don't use any more post-smartphones and texting - what incentive is there to be the first to undercut the others? You can have a plan ready to go as soon as one of the other companies does so, and just wait. I'm fairly convinced I just described the cell phone market in the United States in a nutshell. On the other hand, if a company doesn't know all the other players in a market, or there are simply too many to monitor, then this doesn't work, or at least it doesn't work as well, since it's more likely someone will just take the action.
This is the modern problem with oligopolies. Yet this is not collusion under the law, because they did not agree with each other to price fix ahead of time. The solution would be to create a legal antitrust framework based on effect rather than intent. If the effect is to constrain the market, there are too few players in it. These effects break markets and have higher prices than would otherwise be without them, and thus stifle innovation, as well as create every other consequence that monopolies provide. In reality, the intent is just not important. Unless of course, you just want to support the big corporate interests, rather than a working overall system...
Of course it also must be stated that the current pro-business politicos and regulators are very unlikely to give a damn about enforcing even our standing antitrust practices, as demonstrated int he Comcast/NBC merger, let alone the expanded version needed to get capitalism to make sense as a public good again. In fact, I think the FCC/DOJ's review (as opposed to lawsuits) does look at effect rather than intent, but as they seem to pretty much rubber stamp anything that's not useful. It's ironic that they're always yelling about capitalism's virtues, yet support monopolistic practices which are decidedly anti-capitalist. This is true whether based in intent or effect. Adam Smith understood that, as he was "almost fanatical in his opposition to any kind of monopoly power." It just makes sense - a market is a huge feedback system, and any sort of monopoly effect breaks the feedback loop so that it ceases to function. If we're relying on markets for something, who cares why they broke? Do you only call your plumber if someone intentionally clogged your drain?
So, anyway, I think we need some new, useful antitrust laws. Unless I'm misunderstanding how they currently work, in which case, I'd love to be informed.
