It’s little wonder why lawmakers would want to speed self-driving cars to market. About 90% of traffic accidents are caused by human error and a computer behind the wheel could all but eliminate the risks posed by human drivers: Distraction, drunkenness, speeding, or slow reaction times.

But fallible humans are lucrative for cities. The money from fines for speeding, cruising through stop signs, and lesser infractions like parking violations generate hundreds of millions of dollars for city coffers around the world, helping to pay for infrastructure and even court budgets.

But a city of autonomous, law-abiding cars and trucks, could spell the end of moving violations and traffic tickets.

New York City collected $569 million of parking and traffic fines in the 2016 fiscal year, accounting for 57% of all the fines the city raked in. It’s a small amount compared with the city’s roughly $80 billion-a-year budget, but a significant drop could mean higher taxes or cuts to other basic services at a time when city infrastructure is already stretched.

A decline in revenue from tickets could be more painfully felt in places that rely more on fines. A 2015 investigation by 9News and PBS I-News found five Colorado towns relied on traffic fines for at least 30% of their budgets. These fines comprised almost the entire budget of one town. The Nevada Supreme Court complained in 2015 that a decline in traffic tickets was crimping the court’s budget.

States will be forced to come up with other ways to bridge the gap if and when safe self-driving vehicles become commonplace. But the safety and societal benefit of phasing out that source of revenue could be far-reaching. Traffic accidents cost the US $871 billion a year, according to the National Highway Traffic Safety Administration. Traffic and parking tickets, and harsh penalties for missed payments can keep low-income citizens in a cycle of poverty.