[Futurebot]

There are two things. One, many of the steam units have a knob which doesn't actually work (landlords seal/paint it to the point that you cannot move it.) One of the apartments I grew up in in Brooklyn had one of these "units", and according to my grandmother, the knob hadn't worked in many decades (she started living in that apartment in ~1930.) How this came to be is definitely a mystery.

Two, some steam apartments don't have a unit at all, just a pipe from floor to ceiling. Older tenements feature these (the one I'm living in now has one, for example.) If you want to adjust the temperature with this, your only choices are A/C or the window. These apartments were just built this way, and this was likely the cheapest/only tech available at the time.