This morning, I had the pleasure of driving my brother Ben and his wife Jenna to the airport. Ben and Jenna are a bright pair of semi-newlyweds with a two-story on the Hill and a little dog named Rocco. Ben is a resident at Barnes Jewish Hospital, and Jenna works in deaf education at the Central Institute for the Deaf. Naturally, the pair care a great deal about St. Louis and their community.

With the election still fresh in all of our minds, politics was the topic of discussion — more specifically, Proposition M. At some point, right around Eager and I-64, the two were surprised to hear that I was not shedding tears for the half-cent sales tax’s failure to pass.

While I tried to defend my position, noting how Metro has a poor history of managing funds, the possible reallocation of crime, and, of course, how just because you throw tax money at something doesn’t mean the problem will be solved. But, to my brother and sister-in-law, they saw no possible downside to public transportation.

There are always externalities, whether they are positive or negative. Yes, public transportation does lower carbon emissions and can lower our dependence on foreign oil, but I bet shop owners in the Galleria would say those benefits do not justify the costs of increased shoplifting.

Are there ways around this negative externality? Sure. The Galleria has already put into effect an age limit and curfew for young shoppers. Anyone younger than 16 is required to be accompanied by a parent after 3 p.m. How about on the Metro side? Is the honor system truly cost effective? I rode the MetroLink twice a day this summer for three months, and not once was I asked for a ticket. In fact, the first time I was asked for a ticket was this Monday. New York and Chicago have turnstiles and gates for their public trains. Would increased security in St. Louis be too big of a hurdle?

I see three occurrences that might result from adding new security infrastructure. First, people who need to ride the MetroLink and already buy tickets would continue to do so with little or no effect on their commutes. Second, people who frequent the Metro on a semi-regular basis, who sometimes buy a ticket and sometimes do not, will find only a minimal increase to their MetroLink costs. Third, individuals who often abuse the honor system — constituting a majority of the free rider problem — will either finally pay for their passes or use a different form of transportation. Either way, the only real cost Metro would incur is the initial installation of turnstiles and gates, and whatever maintenance and upkeep costs they require.

While Ben and Jenna are devoted to keeping public transportation cheap and available, I hope I can convince them that there are alternatives to a tax hike that might achieve the same end. I agree that any cuts in line service would be devastating to some people, but it is not up to the taxpayers to dig Metro out of trouble they put themselves in. Apparently, judging by the election results, a majority of people agree with me.