Train hours, why?

Howdy, legit question here - is there a reason the trains in a major is city don’t run 24 hours? I realize other places have limited hours for trains but it’s also way way way cheaper to get places late night without them than it is here.

Is it funding? Ridership? “Safety”? Some weird city contract with rideshare and cab companies? I really do not know because this is for sure a night life city.

Follow up: how do we get late night trains?

This question brought to you by a carless person who needs to be at the airport at 3am :/