UNTIL the 1970s, Major League Baseball was a populist sport. Bleacher seats cost as little as a dollar, meaning middle- or even working-class fans could afford to take their families to a game a few times each season.

But in the years since, tickets to baseball games  along with other professional sports events  have skyrocketed in cost. Over the last two decades, the average ticket price for a Chicago Cubs game has increased 265 percent, more than four times the inflation rate. Add in parking, concessions and souvenirs, and a family trip to one of this week’s opening day games could easily cost a few hundred dollars.

There are many reasons for the price explosion, but a critical factor has been the ability of businesses to write off tickets as entertainment expenses  essentially a huge, and wholly unnecessary, government subsidy.

These deductions have led to higher ticket prices in two ways. On the demand side, they have fueled competition for scarce seats, with business taxpayers bidding in part with dollars they save through the deductions.