Every weekday in New York City, close to one million bus riders — roughly one out of every two passengers — board without paying. The skipped fares are a crucial and growing loss of revenue for the Metropolitan Transportation Authority, which is under severe financial pressure.

New York’s long-running fare evasion problem, among the worst of any major city in the world, has intensified recently; before the pandemic, only about one in five bus riders skipped the fare.

Yet public officials have done relatively little to collect the lost revenue from bus riders. Instead, they have focused almost exclusively on the subway system, where waves of police officers and private security guards have been deployed to enforce payment, even as fare evasion rates on trains are dwarfed by those on buses.

During the first three months of this year, 48 percent of bus riders did not pay, according to the latest available statistics from the transit authority, while 14 percent of subway riders evaded fares. Roughly twice the number of people ride the city’s subways as ride its buses.

Fare evasion has led to startling financial losses for the M.T.A., the state agency that runs the city transit system. In 2022, the authority lost $315 million because of bus fare evasion and $285 million as a result of subway fare beaters, according to a 2023 report commissioned by the M.T.A.

Transit experts say some New Yorkers don’t pay to board the bus because they cannot afford the fare. Others find it far easier to board a bus without paying than to sneak into the subway system, where turnstiles and gates block access. The standard fare for subway riders and most bus passengers is $2.90 per trip.