Glenn Harlan Reynolds

Why do politicians get so excited over things like streetcars and “light rail?” What’s wrong with buses?

The answer isn’t that politicos are train aficionados, but rather the standard answer for why politicians don’t like some things as much as they like others: Insufficient opportunities for graft.

You see, the problem with buses is that you can change a bus route by printing up some new maps. Routes for things that run on rails, on the other hand, are harder to change.

That would seem to be a mark in favor of buses, right? They’re much more flexible. But when you think about opportunities for graft, buses come up short.

Trains offer two advantages: First, all those tracks have to be laid, which means more construction contracts. (If it’s a subway, even better — digging tunnels is worth years, even decades sometimes, of construction work).

But more importantly, property along the rail lines, and especially near the stations, becomes more valuable in most cases. Developers are thus encouraged to cough up big consideration (sometimes actual bribes, sometimes bribes disguised as political support) to politicians to get the stations put where they want. And one reason they’re willing to pay big is that, once the rails are laid and the stations are built, the politicians can’t go back on their word. A development along a bus line isn’t worth as much because you have only a politician’s unsupported promise not to move it, and nobody much trusts a politician’s unsupported promises. As Bloomberg View’s Megan McArdle observes: “So, ironically, the very fact that it is a big, risky investment may help everyone agree to rapidly develop a streetcar route, generating tax revenue for a city, cash for developers, and votes and campaign contributions for the politicians who install the thing. It's hideously inefficient, of course ... but that's politics for you.”

Want to know why voters are so mad? Mia Love has the answer: Glenn Reynolds

This analysis goes far beyond buses. The explanation for why politicians don’t do all sorts of reasonable-sounding things usually boils down to “insufficient opportunities for graft.” And, conversely, the reason why politicians choose to do many of the things that they do is ... you guessed it, sufficient opportunities for graft.

That graft may come in the form of bags of cash, or shady real-estate deals, or “consulting” gigs for a brother-in-law or child, but it may also come in broader terms of political support and even in opportunities for politicians to feel superior or to humiliate their enemies. What all these things have in common, though, is that they’re not about making life better for voters. They’re about making life better for politicians.

This doesn’t sound much like the traditional view of politics, as embodied in, say, the Schoolhouse Rock “I’m Just A Bill” video. But it’s a view of politics that explains an awful lot.

And there’s a whole field of economics based on this view, called “Public Choice Economics.” Nobel prize winning economist James Buchanan referred to public choice economics as “politics without romance.” Instead of being selfless civil servants motivated solely by the public good, public choice economics assumes that politicians are, like other human beings, heavily influenced by self-interest.

Presidential power grabs distort democracy: Goodlatte

POLICING THE USA: A look at race, justice, media

Public choice economists say that groups don’t make decisions, individuals do. And individuals mostly do what they think will be best for them, not for the “public.” Public choices, thus, are like private choices. You pick a car because it’s the best car for you that you can afford. Politicians pick policies because they’re the best policies — for them — that they can achieve.

How do they get away with this? First, most voters are “rationally ignorant.” That is, they realize that their vote isn’t likely to make much of a difference, so it’s not rational to learn all the ins and outs of policy or of what political leaders are doing. Second, the entire system is designed — by politicians, naturally — to make it harder for voters to keep track of what politicians are doing. The people who have a bigger stake in things — the real estate developers or construction unions — have an incentive to keep track of things, and to influence them, that ordinary voters don’t.

Can we eliminate this problem? Nope. But we can make it worse, or better. The more the government does and the more decisions that are relegated to bureaucrats, “guidance” and other forms of decisionmaking that are far from the public eye, the more freedom politicians have to pursue their own interest at the expense of the public — all while, of course, claiming to do just the opposite. Meanwhile, if we do the opposite — give the government less power and demand more accountability — politicians can get away with less. But they’ll always get away with as much as they can.

Some of you may find this analysis of politicians’ behavior too harsh. To which I respond: You probably wouldn’t trust most politicians to babysit your kids. So why do you trust them with bigger issues?

Glenn Harlan Reynolds, a University of Tennessee law professor, is the author of The New School: How the Information Age Will Save American Education from Itself, and a member of USA TODAY's Board of Contributors.

In addition to its own editorials, USA TODAY publishes diverse opinions from outside writers, including our Board of Contributors.To read more columns like this, go to the Opinion front page.