What will it take to get crime under control in our subways and public transit systems?

On Monday, news broke of another passenger set on fire in New York City’s subway — though this story wasn’t all it seemed.

The homeless man who at first said he was the victim of an attack turned tight-lipped when police pressed him about what happened.

Had he set his own clothes ablaze to attract attention?

In the wild environment our subways have become, a malicious attack or a madman’s self-inflicted injury are both all too believable.

Most trips on the New York subway or Washington, D.C.’s metro system don’t resemble a clip from “Mad Max,” but sooner or later anyone who rides the rails of our cities regularly encounters insanity, aggression and the prospect of violence.

The life-changing and very nearly life-ending attack on Bethany MaGee, the woman set aflame on a Chicago Blue Line train last month, was no hoax. Nor was the assault that killed Iryna Zarutska on a commuter train in Charlotte, N.C., this summer.

Nor was the burning alive of Debrina Kawam on the New York subway last December.

None of those women had any reason to fear for her life, yet a commute turned into unspeakable terror.

If a thug with 72 arrests to his name, like the man who tried to immolate the 26-year-old MaGee in Chicago — or with “just” 14 arrests, like Iryna’s murderer — decides this is the day to take an unsuspecting victim, what chance does she have? Her fate was already decided by judges who chose not to lock up men who were a threat to the public.

The killers and would-be killers are only half the problem. The other half are the judges and lawmakers who put them on the streets in the first place.

Legislators in North Carolina, at least, are trying to stop this murderous chain of events before it begins, by putting men with criminal records like those of Iryna’s killer in prison or mental institutions as soon as they start breaking the law.

“Iryna’s Law” restricts cashless bail, requires judges to order more mental evaluations, and makes it easier to involuntarily commit offenders found to be disturbed.

The law is a good start, and other states need similar reforms to incarcerate and institutionalize more of the people who commit horrors like the subway attacks of recent months.

There’s a federal role in this, too, including rigorous enforcement of immigration law.

Yet more is needed: Not only zero tolerance toward violent and repeat offenders but zero tolerance in the political process for judges who go easy on them. Some states elect judges, and voters in those places can make known just how they feel about judges’ culpability for crimes committed by the lawbreakers they set loose.

Five years ago, progressives were pushing, in all seriousness, to “defund the police” and “abolish bail.”

In most of the country, those slogans were not political winners, but advocates for these policies count more on elite sympathy, especially within the legal profession, than they do on ballot-box victories.

Their gamble is that most Americans pay no mind to the inner workings of state courts and legislatures, so what loses in an election can still win where laws and legal precedents are made.

Leaders in states and cities have betrayed Americans’ trust, and their betrayal turns public transportation into scenes of public execution for innocents like Iryna Zarutska.