If you're old enough you might remember Americans were much more violent from 1960 to 1995 or so and the crime rate was incredibly high in American cities, leading to what was called white flight.
Now, if you work with young people (so-called zoomers), you'll notice they are absolutely not like this anymore.
At least 30% of this was caused by everyone breathing leaded gasoline.
Your problem is you're watching the news, don't do that. (The rate of news articles is pretty much never connected to how much crime there actually is.)
NYC is more or less the safest place in the world; it's certainly the safest place in the US. And the remaining danger is getting hit by cars, not in the subway.